Gelatinous cushions with buckling columns

ABSTRACT

A cushioning element that has a number of substantially parallel elongate columns which buckle under an appropriate load. The cushioning element may be formed from a soft, easily deformable elastic or visco-elastic cushioning media. As a force is exerted against the cushioning element generally parallel to a column, the cushioning media may compress, and eventually the walls of the column may buckle. This equalizes pressure across the contact area of the object being cushioned.

This patent application is a continuation-in-part application of U.S.patent application Ser. No. 08/601,374, filed on Feb. 14, 1996, now U.S.Pat. No. 5,749,111 and priority is claimed thereto for all of thematerial disclosed either explicitly or inherently therein.

I. BACKGROUND OF THE INVENTION

A. Field of the Invention

This invention relates to the field of cushions. More particularly, thisinvention relates to a cushion made of gelatinous elastomer, gelatinousvisco-elastomer, or materials with similar characteristics which hashollow columns that compress to provide cushioning and which buckle torelieve pressure peaks.

B. The Background Art

In the prior art, there have been numerous attempts to provide a cushionwhich achieves comfort by eliminating peak pressure areas and by evenlydistributing the cushioning force over a broad surface area. Therelevant prior art of which the inventor is aware is categorized andsummarized below.

1. Foam Cushions: Foam cushions typically include open cell polyurethanefoam because of its low cost and light weight. The open cells are, ineffect, air bubbles within the polyurethane which can be compressed andfrom which air can escape when a force, such as the weight of acushioned object, is placed on the foam. Alternatively, foam cushionsmay use closed cell foam, in which the cells contain air or another gas,but the cells are closed so that the air or gas cannot escape even whena compressive force is applied to the foam. Closed cell cushions tend toresist deformation more than similarly constructed open cell cushions.In function, foam cushions behave much the same as a spring, permittingthe cushioned object to sink into the foam and to be supported byrebound pressure; the more the cushioned object sinks into the foam, thehigher the rebound pressure. When the cushioned object is removed, thefoam has a tendency to return to its original shape, a characteristicreferred to as "shape memory."

A significant problem with foam cushions is that protruding portions ofthe object being cushioned are placed under the highest pressure due tothe foam's spring-like behavior, resulting in pressure on the cushionedobject not being equalized. "Pressure peaks," as defined herein, meansareas of a cushioned object which are subject to the greatest amounts ofpressure when placed upon a cushioning surface. Closed cell foamcushions tend to create even worse pressure peaks than open cell foamcushions due to their inability to permit gas to escape from their cellswhen the cushion is called on to support an object.

Examples of cushions that include foam are included in the followingdocuments: U.S. Pat. No. 4,713,854 issued in the name of Graebe on Dec.22, 1987; U.S. Pat. No. 4,709,431 issued in the name of Shaktman on Dec.1, 1987; U.S. Pat. No. 4,628,557 issued in the name of Murphy on Dec.16, 1986; U.S. Pat. No. 4,467,053 issued in the name of Markle on Aug.21, 1984; U.S. Pat. No. 3,518,786 issued in the name of Holtvoigt onJul. 7, 1970; and U.S. Pat. No. 5,335,907 issued in the name of Spectoron Aug. 9, 1994, each of which is hereby incorporated in its entiretyfor the material disclosed therein.

The following patents include both foam and a gel or fluid (seediscussion of gels below): U.S. Pat. No. 4,952,539 issued in the name ofHanson on Aug. 29, 1990; U.S. Pat. No. 5,147,685 issued in the name ofHanson on Sep. 15, 1992; U.S. Pat. No. 5,058,291 issued in the name ofHanson on Oct. 22, 1991; U.S. Pat. No. 5,255,404 issued in the name ofDinsmoor, III et al. on Oct. 26, 1993; U.S. Pat. No. 5,201,780 issued inthe name of Dinsmoor, III et al. on Apr. 13, 1993; U.S. Pat. No.4,842,330 issued in the name of Jay on Jun. 27, 1989; and U.S. Pat. No.4,726,624 issued in the name of Jay on Feb. 23, 1988, each of which ishereby incorporated in its entirety for the material disclosed therein.

2. Fluid Cushions: Some in the prior art have attempted to design acomfortable cushion using some type of a flowable fluid (such as liquid,air, gas, emulsion, lubricated objects or particles, etc.) within one ormore fluid-tight bladders. When an object is placed on the fluidcushion, or when an object resting on the cushion is re-positioned, thefluid flows within the bladder and the bladder correspondingly deformsto conform to the shape of the object being cushioned. This results in acushion which tends to equally distribute a cushioning pressure acrossthe entire contact surface of the object being cushioned, and maximizesthe percentage of the surface area of the object which is underpressure. Correspondingly, this also eliminates or reduces pressurepeaks on the cushioned object.

Prior art fluid cushions have a number of problems, however. First, whenthe object being cushioned is shifted or repositioned on the fluidcushion, instability may result. Second, depending upon the type offluid used, the cushion may have a high thermal mass and a high rate ofthermal transfer, resulting in a cushion which is cold to the touch andwhich tends to draw heat out of the object being cushioned. This canresult in discomfort when the object being cushioned is a human being.Third, fluid cushions are typically very costly to manufacture. Fourth,due to the necessity of maintaining a fluid-tight bladder, fluidcushions may be unreliable due to the possibility of bladder puncture.Fifth, if a fluid cushion is not of sufficient thickness, the objectbeing cushioned may displace enough of the cushioning fluid to bottomout against a base on which the fluid bladder is resting, resulting inlittle or no cushioning effect. Sixth, fluid cushions have little shapememory, so they do not return to their original shape when the cushionedobject is removed. Consequently, fluid cushions do not have anaesthetically pleasing appearance and are typically not consideredappropriate for furniture. Seventh, fluid cushions typically do notpermit good air circulation between the cushioned object and thecushion, resulting in moisture building up between the cushioned objectand the bladder (e.g., perspiration from a human body). And eighth, many(but not all) prior art fluid cushions tended to be very heavy. However,fluid cushions which use the composite mixture disclosed in U.S. Pat.Nos. 5,421,874, 5,549,743 and 5,626,657, each of which issued in thename of Pearce, tend to be lightweight.

Examples of fluid cushions include the following: United Kingdom PatentNo. 1,261,475 which was published on Jan. 26, 1972; U.S. Pat. No.5,369,828 issued in the name of Graebe on Dec. 6, 1994; U.S. Pat. No.5,103,518 issued in the name of Gilroy et al. on Apr. 14, 1992; U.S.Pat. No. 4,945,588 issued in the name of Cassidy et al. on Aug. 7, 1990;U.S. Pat. No. 4,737,998 issued in the name of Johnson, Sr. on Apr. 19,1988; U.S. Pat. No. 4,485,505 issued in the name of Paul on Dec. 4,1984; U.S. Pat. No. 4,292,701 issued in the name of Woychick on Oct. 6,1981; U.S. Pat. No. 3,462,778 issued in the name of Whitney on Aug. 26,1969; U.S. Pat. No. 2,672,183 issued in the name of Forsyth on Mar. 16,1954; U.S. Pat. No. 2,814,053 issued in the name of Sevcik on Nov. 26,1957; U.S. Pat. No. 2,491,557 issued in the name of Goolsbee on Dec. 20,1949; U.S. Pat. No. 5,100,712 issued in the name of Drew et al. on Mar.31, 1992; U.S. Pat. No. 5,255,404 issued in the name of Dinsmoor, III etal. on Oct. 26, 1994; U.S. Pat. No. 5,204,154 issued in the name of Drewet al. on Apr. 20, 1993; U.S. Pat. No. 5,201,780 issued in the name ofDinsmoor, III et al. on Apr. 13, 1993; U.S. Pat. No. 5,147,685 issued inthe name of Hanson on Sep. 15, 1992; U.S. Pat. No. 5,058,291 issued inthe name of Hanson on Oct. 22, 1991; U.S. Pat. No. 5,020,176 issued inthe name of Dotson on June 4, 1991; U.S. Pat. No. 5,018,790 issued inthe name of Jay on May 28, 1991; U.S. Pat. No. 5,093,138 issued in thename of Drew et al. on Mar. 3, 1992; U.S. Pat. No. 4,842,330 issued inthe name of Jay on Jun. 27, 1989; U.S. Pat. No. 4,761,843 issued in thename of Jay on Aug. 9, 1988; U.S. Pat. No. 4,728,551 issued in the nameof Jay on Mar. 1, 1988; U.S. Pat. No. 4,726,624 issued in the name ofJay on Feb. 23, 1988; U.S. Pat. No. 4,660,238 issued in the name of Jayon Apr. 28, 1987; U.S. Pat. No. 4,588,229 issued in the name of Jay onMay 13, 1986; U.S. Pat. No. 4,483,029 issued in the name of Paul on Nov.20, 1984; U.S. Pat. No. 4,255,202 issued in the name of Swan, Jr. onMar. 10, 1981; U.S. Pat. No. 4,247,963 issued in the name of Reddi onFeb. 3, 1981; U.S. Pat. No. 4,243,754 issued in the name of Swan, Jr. onJan. 6, 1981; U.S. Pat. No. 4,229,546 issued in the name of Swan, Jr. onOct. 21, 1980; U.S. Pat. No. 4,144,658 issued in the name of Swan, Jr.on Mar. 20, 1979; U.S. Pat. No. 4,083,127 issued in the name of Hansonon Apr. 11, 1978; U.S. Pat. No. 4,038,762 issued in the name of Swan,Jr. on Aug. 2, 1977; U.S. Pat. No. 3,968,213 issued in the name of Lynchon Oct. 19, 1976; and U.S. Pat. No. 3,748,669 issued in the name ofWarner on Jul. 31, 1973, each of which is hereby incorporated byreference in its entirety for the material disclosed therein.

3. Gel Cushions: Another design which those in the prior art attemptedto employ to create an effective cushion included the use of gelatinousmaterials ("gels"). Gelatinous materials are soft elastic orviscoelastic materials which easily deform but return to their originalshape after the deforming force is removed. The prior art gel cushionshad one or more of the following problems. First, gel cushions had ahigh thermal mass and a high coefficient of thermal transfer, makingthem cold to the touch and causing them to drain heat out of a cushionedobject. Second, gel cushions tended to be costly to manufacture. Third,gel cushions had limited compressibility and therefore did not permitthe cushioned object to sink deep into the gel. As a result, only asmall surface area of the cushioned object is cushioned by a prior artgel cushion, resulting in a greater supporting force being applied onthat small surface area than would be applied if a greater surface areaof the cushioned object were to contact the gel cushion for support.This is because in order for the cushioned object to sink into prior artgel cushions, the cushions, which tended to be relativelyincompressible, must expand in directions generally normal to thedirection of the intended sinking, a behavior which cannot beaccommodated in most cushioning applications.

Notwithstanding their problems in the prior art, gel cushions have someattractive features. For example, a gel cushion permits anear-hydrostatic pressure distribution across the surface area of thecushioned object if the cushioned object is allowed to sink into the geland the overall dimensions of the cushion are not restricted so thatsuch sinking in would be prevented. Also, many gel cushions have theaesthetic advantage, through their shape memory, of being capable ofreturning to their original shape after the cushioned object is removed.

Documents which disclose gel cushions include: U.S. Pat. No. 5,456,072issued in the name of Stern on Oct. 10, 1995; U.S. Pat. No. 5,362,834issued in the name of Schapel et al. on Nov. 8, 1994; U.S. Pat. Nos.5,336,708, 5,334,646, 5,262,468, 4,618,213 and 4,369,284, each of whichissued in the name of Chen; U.S. Pat. No. 5,191,752 issued in the nameof Murphy on Mar. 9, 1993; and U.S. Pat. No. 4,913,755 issued in thename of Grim on Apr. 3, 1990, each of which is hereby incorporated byreference in its entirety.

4. Thermoplastic Film Honeycomb Cushions: Another type of cushion in theprior art is made from multiple perforated sheets of pliablethermoplastic film which are intermittently welded together and thenexpanded into a pliable plastic honeycomb. Honeycomb cushions may haveproblems such as a high cost of manufacture and an inability to equalizesupporting pressure in order to avoid pressure peaks on the mostprotruding parts of the object being cushioned. This is because of therelatively rigid nature of the thermoplastic and thermoplastic elastomerfilms used in the honeycomb cushion construction. Honeycomb cushionsalso carry the risk that the cushioned object will bottom out throughthe cushion. This is because the films are thin and relatively rigid, socollapsed cells within the cushion offer no real cushioning effect.

The advantages of honeycomb cushions include their light weight. Most ofthe cushion consists of voids within the cells of the honeycomb, thevoids being filled with air, resulting in a lightweight cushion. Anotheradvantage is that honeycomb cushions provide good air circulationbetween the cushioned object and the cushion due to the perforations inthe cell walls of the honeycomb and/or in the facing sheets above andbelow the honeycomb cells.

Examples of honeycomb or multilayer film cushions are as follows: U.S.Pat. No. 5,445,861 issued in the name of Newton et al. on Aug. 29, 1995;U.S. Pat. No. 5,444,881 issued in the name of Landi et al. on Aug. 29,1995; U.S. Pat. No. 5,289,878 issued in the name of Landi on Mar. 1,1994; U.S. Pat. No. 5,203,607 issued in the name of Landi on Apr. 20,1993; U.S. Pat. No. 5,180,619 issued in the name of Landi et al. on Jan.19, 1993; U.S. Pat. No. 5,015,313 issued in the name of Drew et al. onMay 14, 1991; U.S. Pat. No. 5,010,608 issued in the name of Barnett etal. on Apr. 30, 1991; U.S. Pat. No. 4,959,059 issued in the name ofEilender et al. on Sep. 25, 1990; and U.S. Pat. No. 4,485,568 issued inthe name of Landi et al. on Dec. 4, 1984, each of which is herebyincorporated by reference in its entirety.

5. Mattressing: In the prior art there has been work in the field ofmattressing, which is considered to be related background against whichthe invention was made. For references with disclosure relevant tomattressing, the reader is directed to United Kingdom Patent No.1,261,475 which was published on Jan. 26, 1972; U.S. Pat. No. 5,369,828issued in the name of Graebe on Dec. 6, 1994; U.S. Pat. No. 5,103,518issued in the name of Gilroy et al. on Apr. 14, 1992; U.S. Pat. No.4,945,588 issued in the name of Cassidy et al. on Aug. 7, 1990; U.S.Pat. No. 4,737,998 issued in the name of Johnson, Sr. on Apr. 19, 1988;U.S. Pat. No. 4,485,505 issued in the name of Paul on Dec. 4, 1984; U.S.Pat. No. 4,292,701 issued in the name of Woychick on Oct. 6, 1981; U.S.Pat. No. 3,462,778 issued in the name of Whitney on Aug. 26, 1969; U.S.Pat. No. 2,672,183 issued in the name of Forsyth on Mar. 16, 1954; U.S.Pat. No. 2,814,053 issued in the name of Sevcik on Nov. 26, 1957; andU.S. Pat. No. 2,491,557 issued in the name of Goolsbee on Dec. 20, 1949,each of which is hereby incorporated by reference.

The reader will find that the prior art thus had numerous shortcomingswhich are addressed by the invented cushion, as outlined below.

II. SUMMARY OF THE INVENTION

It is an object of the invention to provide a cushion that distributessupporting pressure on an object being cushioned in a manner that isgenerally even and without pressure peaks. It is a feature of theinvention that the cushion has a low surface tension and permits acushioned object to sink deeply into it. This action is due tocompressibility of the cushion. It is also a feature of the inventedcushion that some of the columns present in the invented cushion tend tobuckle under the weight of the object being cushioned. This buckling isespecially useful in accommodating protrusions from the object beingcushioned into the cushion. The ability to accommodate protrusionsthrough buckling of the cushion columns eliminates pressure peaks. It isa consequent advantage of the invention that the invented cushion iscomfortable and does not tend to constrict blood flow in the tissue of ahuman being on the cushion, thus being suitable for medical applicationsand other applications where the object being cushioned may be immobilefor long periods of time, such as in automobile seats, furniture,mattresses, and other applications.

It is an object of the invention to provide a cushion that eliminatespressure peaks on an object being cushioned. It is a feature of theinvention, as mentioned above, that the invented cushion includescolumns which buckle under protuberances on a cushioned object. As aresult, the cushioned object is not exposed to pressure peaks.

It is an object of the invention to maximize the surface area of thecushioned object that is in contact with the cushion by permitting thecushioned object to sink deeply into the cushion, without the prior artproblem that exterior surfaces of the cushion that are not in the planein contact with the cushioned object must expand. It is a feature of theinvented cushion that the cushion is compressible and that the cushionincludes columns within it that can buckle under the weight of thecushioned object. The bottom of the cushion and its outside periphery,not including the surface of the cushion in contact with the cushionedobject, may, if desired, be restrained, but the compressibility andbucklability of the cushion will still permit the cushioned object tosink into the cushion. It is an advantage of the invention that a gelcushion is provided which can have a constrained periphery but whichwill still permit a cushioned object to sink deeply into it.

It is an object of the invention to provide a cushion that eliminatesthe head pressure found in some fluid cushions. In fluid cushions, theflowable media may be drawn by gravity so that it exerts pressure onsome portions of the cushioned object as the cushioning media attemptsto flow in response to the gravitational force. This pressure isreferred to as "head pressure." Head pressure can cause discomfort andtissue damage to a human using the cushion. The gel from which theinvented cushion is made does not develop head pressure.

It is an object of the invention to provide a cushion which isinexpensive to manufacture compared to prior art cushions. It is afeature of the invention that the invented cushion may be very quicklyand cheaply injection molded or cast from suitable low cost gelmaterials. It is an advantage of the invention that a cushion whichincorporates the features of the invention may be produced forsubstantially less cost than prior art cushions with comparableperformance characteristics.

It is an object of the invention to provide a cushion that is stable asthe center of gravity of the cushioned object is shifted. It is afeature of the invention that a cushioned object may sink deeply intothe cushion. It is also a feature of the invention that the gel of theinvented cushion does not allow flow of the cushioning media as in fluidcushions. It is another feature of the invented cushion that it isadapted to accommodate the sinking in of an object but tends to berelatively rigid in a horizontal direction and thus resist horizontaldisplacing forces. Consequently, an object being cushioned by theinvented cushion can be shifted on the cushion without a tendency of thecushion to move unpredictably underneath the cushioned object. As aresult, the invented cushion displays a high degree of stability.

It is an object of the invention to provide a cushion that will not loseits structural integrity or cushioning effect if punctured. It is afeature of one preferred embodiment of the invention that the gel usedto make the cushion is a solid (although a flexible, resilient solid) atordinary room temperatures (i.e. below 130° Fahrenheit). Thus, even ifthe cushion is punctured, there is no escape of cushioning media, aswould occur if a prior art fluid cushion were punctured. It is thus anadvantage of the invention that superior durability is provided in thecushion.

It is an object of the invention to provide a cushion that has shapememory. It is a feature of the invented cushion that a gel is used tomake the cushion that tends to return to its original shape after adisplacing force (such as the gravitational force exerted on a cushionedobject) is removed. It is an advantage of the invention that attractivecushions suitable for devices such as furniture, automobile seats,theatre seats, etc. are provided. Prior art fluid cushions were notdesirable for such applications because they tended to retain the shapeof the cushioned object after the cushioned object was removed. This wasconsidered unsightly. The invented cushion, in contrast, returns to itsorignal, as-new shape after the cushioned object is removed.

It is an object of the invention to provide a cushion which provides asuperior amount of air circulation between the cushion and the cushionedobject in comparison to the prior art. It is a feature of the inventionthat hollow columns are provided in one preferred embodiment of theinvention through which air may circulate. The surface area of thecushioned object that is in contact with the cushion is therefore incontact only with the perimeter rims of the hollow columns. Thus, mostof the surface area of the cushioned object within the perimeter of theoutermost points of contact between the cushioned object and the cushionis exposed to air circulation through the hollow columns. It is thus anadvantage of this structure that heat buildup between the cushionedobject and the cushion is lessened in comparison with the prior artcushions. If the cushioned object is a human being, this structureprovides the human being with far greater comfort than prior artcushions because the invented cushion will facilitate rapid evaporationof sweat rather than causing a sweat buildup as in prior art cushions.

It is an object of the invention to provide a cushion that islightweight. This is an important object for all applications of theinvention, but particularly important for medical applications. It is afeature of the invention that the invented cushion includes a number ofhollow columns so that the predominant volume of space occupied by thecushion is actually occupied by a gas such as air. Consequently, thetotal weight of the cushion is low.

It is an object of the invention to provide a cushion that has a lowrate of thermal transfer and a low thermal mass. Many prior artcushions, such as fluid cushions, felt cold to the touch and tended todraw heat out of a human being resting on the cushion. This causeddiscomfort to the human being. The invented cushion occupies a volume ofspace predominantly with a gas such as air which has a low thermal mass.It is an advantage of the invention that the cushion has a substantiallyreduced tendency to feel cold to the touch, compared to the prior art,and that the cushion does not tend to draw heat from the object beingcushioned. The result is a comfortable cushion.

It is an object of the invention to provide a cushion that will offercushioning protection to a cushioned object even if the cushioned objecthas bottomed out within the cushion. A cushioned object is considered tohave bottomed out within a cushion if it has sunk into the cushionbeyond the point where the normal cushioning mechanism is effective. Analternative way of stating this is that the cushioned object has sunkinto the cushion to the extent that a portion of the cushion has beencompressed to an extent that is not further compressible. The inventedcushion, due to the elastic nature of the gel used, tends to have moregive and resiliency than a hard surface, such as a wooden chair, would,even when the cushioned object has bottomed out in the cushion. Ifbottoming out were to occur, the cushion has comparable cushioning tomany gel cushions in the prior art. Thus, the cushion continues toprovide some cushioning effect beneath the portion of the cushionedobject that has bottomed out. Additionally, the cushion will continue tocushion effectively beneath the portion of the cushioned object that hasnot bottomed out within the cushion.

It is an object of the invention to provide a cushion that has a greatrange of compressibility. The invented cushion, in its preferredembodiments, has a substantial depth measurement along its verticalcolumns. The cushioned object sinks into the cushion some portion ofthat depth measurement. The preferred cushion has enough depth andcompressibility that the cushioned object can be of a very wide range ofweights and still receive effective cushioning from the inventedcushion.

It is an object of the invention to provide a cushion that achieves nearhydrostatic pressure distribution across the contact area of the objectbeing cushioned. The compressibility of the gel columns provides goodoverall cushioning, and the buckling of columns beneath the mostprotruding points relieves pressure at the points where pressure tendsto be highest in prior art foam or solid gel cushions.

These and other objects, features and advantages of the invention willbecome apparent to persons of ordinary skill in the art upon reading thespecification in conjunction with the accompanying drawings.

III. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the invented cushion as part of an office chair.

FIG. 2 depicts the invented cushion including its cushioning element andcover.

FIG. 3 depicts a cutaway of the invented cushion of FIG. 1 at 3--3.

FIG. 4 depicts a mold which may be used to manufacture the inventedcushion.

FIG. 5 depicts an alternative mold for manufacturing the inventedcushion.

FIG. 6 depicts a cross sectional view of a cushion manufactured usingthe mold of FIG. 5.

FIG. 7 depicts an isometric view of an alternative embodiment of theinvented cushion.

FIG. 8 depicts a top view of an alternative embodiment of the inventedcushion.

FIG. 9 depicts an isometric view of an alternative embodiment of theinvented cushion.

FIG. 10 depicts a top view of an alternative embodiment of the inventedcushion.

FIG. 11 depicts a cross sectional view of a column of the inventionduring one mode of buckling.

FIG. 12 depicts a cross sectional view of a column of the inventionduring another mode of buckling.

FIG. 13 depicts forces in play as a column buckles.

FIG. 14 depicts an alternative structure for a column and its walls.

FIG. 15 depicts a cross section of a cushion using alternating steppedcolumns.

FIG. 16 depicts an alternative embodiment of the invented cushioningelement having gas bubbles within the cushioning media.

FIG. 17 depicts a cushion of the invention in use with a combinationbase and container.

FIG. 18 depicts a cushion of the invention having side wallreinforcements to support the cushioning element.

FIG. 19 depicts a cushioning element of the invention having a girdle orstrap about its periphery to support the cushioning element.

FIG. 20 depicts a cushioning element of the invention with closed columntops and bottoms and fluid cushioning media contained within the columninteriors.

FIG. 21 depicts a cushioning element of the invention with firmnessprotrusions placed within the column interiors.

FIG. 22 is a frontal perspective view of an embodiment of the cushioningelement of the invention which include multiple individual cushioningunits.

FIG. 23a is a frontal perspective view of an embodiment of thecushioning element of the invention in which a first cushioning mediumis contained within a second cushioning medium.

FIG. 23b is a cross section taken along line 23b--23b of FIG. 23a.

FIG. 23c is a frontal perspective view of an alternate configuration ofthe embodiment shown in FIG. 23a.

FIG. 23d is a cross section taken along line 23d--23d of FIG. 23c.

FIG. 24a is a frontal perspective view of an embodiment of thecushioning element of the invention in which the outer surfaces of thecushioning medium are covered with a coating.

FIG. 24b is a cross section taken along line 24b--24b of FIG. 24a.

FIG. 25a is a perspective view of an embodiment of the cushioningelement of the present invention, wherein the cushion includes multiplesets of parallel columns and wherein each column intersects no columnsof another parallel column set or columns of only one other set.

FIG. 25b is a cross section taken along line 25b--25b of FIG. 25a.

FIG. 25c is a cross section taken along line 25c--25c of FIG. 25a.

FIG. 25d is a perspective view of an alternative configuration of theembodiment shown in FIG. 25a, wherein each column may intersect columnsof any number of the other parallel column sets.

FIG. 25e is a cross section taken along line 25e--25e of FIG. 25d.

FIG. 25f is a cross section taken along line 25f--25f of FIG. 25d.

FIG. 26 is a frontal perspective view of an embodiment of the cushioningelement of the present invention wherein the cushion has multiple setsof parallel narrow columns.

FIG. 27a is a frontal perspective view of an embodiment of thecushioning element of the present invention which includes multiple setsof parallel columns and cavities formed in the column walls.

FIG. 27b is a cross section taken along line 27b--27b of FIG. 27a.

FIG. 27c is a cross section taken along line 27c--27c of FIG. 27a.

FIG. 28 is a frontal perspective view of an embodiment of the cushioningelement according to the present invention which has a contoured surfaceand includes columns of more than one height.

FIG. 29 is a frontal perspective view of an embodiment of the cushioningelement of the present invention wherein the cushioning medium isfoamed.

FIG. 30a is a frontal perspective view of an embodiment of thecushioning element of the present invention wherein the column walls areformed from numerous short tubular pieces, which create voids in thecolumn walls.

FIG. 30b is a frontal perspective view of an alternative configurationof the cushioning element shown in FIG. 30a, wherein the column wallsinclude voids created by extracting space consuming objects therefromfollowing molding of the cushioning medium.

FIG. 31a depicts a carbon atom and its covalent bonding sites.

FIG. 31b depicts a hydrogen atom and its covalent bonding site.

FIG. 31c depicts a four carbon hydrocarbon molecule known as butate.

FIG. 32a depicts a triblock copolymer useful in the preferred cushioningmedium.

FIG. 32b depicts the triblock copolymer of FIG. 32a in a relaxed state.

FIG. 33a depicts the chemical structure of a styrene molecule.

FIG. 33b depicts the chemical structure of a benzene molecule.

FIG. 33c depicts the chemical structure of an aryl group.

FIG. 33d depicts the chemical structure of an -enyl group.

FIG. 33e depicts the chemical structure of an ethenyl group.

FIG. 33f depicts the chemical structure of a propenyl group.

FIG. 34a depicts a midblock (B) of the triblock copolymer of FIG. 32a.

FIG. 34b depicts an endblock (A) of the triblock copolymer of FIG. 32a.

FIG. 34c depicts the weak bonding between the monomer unites of one ormore midblocks (B) of the triblock copolymer of FIG. 32a.

FIG. 34d depicts an endblock (A) of the triblock copolymer of FIG. 32a,showning the endblock (A) in a relaxed state.

FIG. 35a depicts the chemical structure of hydrocarbon molecules knownas alkanes.

FIG. 35b depicts the chemical structure of hydrocarbon molecules knownas alkenes.

FIG. 35c depicts the chemical structure of hydrocarbon molecules knownas alkynes.

FIG. 35d depicts the chemical structure of a hydrocarbon molecule knownas a conjugated diene.

FIG. 35e depicts the chemical structure of a hydrocarbon molecule knownas an isolated diene.

FIG. 36a depicts the chamical structure of a poly(ethylene/butylene)molecule.

FIG. 36b depicts the chemical structure of a poly(ethylene/propylene)molecule.

FIG. 36c depicts the chemical structure of a 1,3-butadiene molecule.

FIG. 36d depicts the chemical structure of an isoprene molecule.

FIG. 37a depicts polystyrene-poly(ethylene/butylene)-polystyrene.

FIG. 37b depicts polystyrene-poly(ethylene/propylene)-polystyrene.

FIG. 37c depicts polystyrene-polybutadiene-polystyrene.

FIG. 37d depicts polystyrene-polyisoprene-polystyrene.

FIG. 37e depicts polystyrene-poly(isoprene+butadiene)-polystyrene.

FIG. 37f depictspolystyrene-poly(ethylene/butylene+ethylene/propylene)-polystyrene.

FIG. 38a depicts the chemical structure ofpolystyrene-poly(ethylene/butylene +ethylene/propylene)-polystyrene.

FIG. 38b depicts the group of the triblock copolymers of FIG. 321a,showing weak attraction of the endblocks to each other.

FIG. 39a illustrates plasticizer association with the group of triblockcopolymers of FIG. 38b according to a preferred formulation of thepreferred cushioning medium.

FIG. 39b illustrates the lubricity theory of plasticization, showing twomidblocks (B) moving away from each other.

FIG. 39c illustrates the lubricity theory of plasticization, showing twomidblocks (B) moving toward each other.

FIG. 39d illustrates the lubricity theory of plasticization, showing twomidblocks (B0 moving across each other.

FIG. 39e illustrates the gel theory of plasticization, showing a weakattraction between two midblocks (B) when plasticizer is not present.

FIG. 39f illustrates the gel theory of plasticization, showing aplasticizer molecule breaking the weak attraction of FIG. 39e.

FIG. 39g illustrates the mechanistic theory of plasticization, showingan equilibrium of plasticizer breaking the weak attraction of midblocks(B) for each other.

FIG. 39h illustrates the free volume theory of plasticization, showingthe free space associated with a midblock (B).

FIG. 39i illustrates the theory of FIG. 39h, showing that as smallplasticizer molecules are added, the free space in a given areaincreases.

FIG. 39j illustrates the theory of FIG. 39h, showing the even smallplasticizers provide an even greater amount of free space.

FIG. 40a depicts the use of an extruder to perform a preferred methodfor foaming the preferred gel cushioning media.

FIG. 40b depicts the use of an injection molding machine to perform apreferred method for foaming the preferred gel cushioning media.

FIG. 41 depicts an embodiment of a cushioning element according to thepresent invention, wherein a plurality of tubes are bonded together toform the cushion.

FIG. 42 depicts a method for bonding the individual tubes of FIG. 41together to form the cushioning element shown therein.

III. DESCRIPTION OF THE PREFERRED EMBODIMENT

A. Configuration of the Cushions

FIG. 1 depicts a cushioned object 101, in this instance a human being,atop of a piece of furniture 102, in this instance a chair, whichincludes the invented cushion 103. Although in this embodiment, theinvented cushion 103 is depicted as part of an office chair, theinvented cushion may be used with many types of products, includingfurniture such as sofas, love seats, kitchen chairs, mattresses, lawnfurniture, automobile seats, theatre seats, padding found beneathcarpet, padded walls for isolation rooms, padding for exerciseequipment, wheelchair cushions, bed mattresses, and others.

Referring to FIG. 2, the cushion 103 of FIG. 1 is depicted in greaterdetail. The cushion 103 includes a cover 204. The preferred cover is adurable and attractive fabric, such as nylon, cotton, fleece, syntheticpolyester or another suitable material which is preferably stretchableand elastic and which readily permits the flow of air through it toenhance ventilation of a cushioned object. Within the cover 204, acushioning element 205 is to be found. As can be seen from FIG. 2, thecushioning element 205 comprises a cushioning media of a desired shape.In the embodiment depicted, the cushioning element 205 includes gelcushioning media formed generally into a rectangle with four sides, atop and a bottom, with the top and bottom being oriented toward the topand bottom of the page, respectively. The cushioning element has withinits structure a plurality of hollow columns 206. As depicted, the hollowcolumns 206 contain only air. The hollow columns 206 are open to theatmosphere and therefore readily permit air circulation through them,through the cover 204 fabric, and to the cushioned object. The columns206 have column walls 207 which in the embodiment depicted are hexagonalin configuration. It is preferred that the total volume of thecushioning element will be occupied by not more than about 50% gelcushioning media, and that the rest of the volume of the cushioningelement will be gas or air. More preferably, the total volume of thecushioning element will be occupied by as little as about 9% cushioningmedia, and the rest of the volume of the cushion will be gas or air.This yields a lightweight cushion with a low overall rate of thermaltransfer and a low overall thermal mass. It is not necessary that thispercentage be complied with in every instance that the inventive conceptis practiced, however.

Referring to FIG. 3, a cushioned object 101, in this instance a humanbeing, is depicted being cushioned by the invented cushion 103 whichincludes cushioning element 205 within cover 204. Also visible is acushion base 301 of a rigid material such as wood, metal, plastic onwhich the cushioning element 205 rests. The cushioning element 206includes hollow columns 206 with walls 207. It can be seen that beneaththe most protruding portion of the cushioned object, in this instance ahip bone 302, the hollow columns 303 have walls 304 which have partiallyor completely buckled in order to accommodate the protuberance 302 andavoid creating a high pressure point below the protuberance 302 inresponse to the compressive force exerted by the cushioned object.Buckled columns offer little resistance to deformation, thus removingpressure from the hip bone area. It can also be seen that in portions ofthe cushioning element 205 which are not under the protuberance 302, thecushioning media which forms the walls 304 of the hollow columns 303 hascompressed but the columns 303 have not buckled, thus loading thecushioned object across the broad surface area of its non-protrudingportions. The cushion is yieldable as a result of the compressibility ofthe cushioning media and the bucklability of the columns (or columnwalls). The cushion 103 is depicted as having been manufactured usingthe mold depicted in FIG. 4. It can be seen from this cushion's responseto a compressive force exerted by the cushioned object that the cushionand the cushioning element are adapted to have a cushioned object placedon top of them.

Referring to FIG. 6, a cross section of an alternative embodiment of theinvention is depicted. The cushioning element 601 includes cushioningmedia 604 (which is preferred to be a gel cushioning media) which formwalls 605 for columns 602, 603. It can be seen that the columns 602 and603 are oriented into a group protruding from the top of the cushioningelement 601 down into the cushioning media 604 but not reaching thebottom of the cushioning element of which column 602 is a member, and agroup protruding from the bottom of the cushioning element 601 into thecushioning element 601 but not reaching the top of the cushioningelement 601 of which column 602 is a member. This yields a generallyfirmer cushion than that shown in some other figures. This cushion wouldbe manufactured by the mold depicted in FIG. 5.

Referring to FIG. 7, an alternative embodiment of a cushioning element701 is depicted. The cushioning element includes cushioning media 702,columns 703 and column walls 704. The columns depicted in FIG. 7 aresquare in a cross section taken orthogonal to their longitudinal axis,in contrast to the columns of FIG. 2 which are hexagonal in a crosssection taken orthogonal to their longitudinal axis. It is also of notethat in FIG. 7, the columns 703 are arranged as an n×m matrix with eachrow and each column of columns in the matrix being aligned perfectlyadjacent to its neighbor, with no offsetting. Examplary sizing andspacing of columns in the invention would include columns which have across sectional diameter taken orthogonal to the longitudinal axis ofabout 0.9 inch and a column wall thickness of about 0.1 inch at thethinnest point on a column wall. Many other dimensions, shapes andspacing of columns and column walls may be employed while practicing theinventive concept.

Referring to FIG. 8, a top view of an alternative cushioning element 801is depicted. The cushioning element 801 includes cushioning media 802which forms column walls 804, columns 803 and an exterior cushioningelement periphery 805. It can be seen that the columns 803 of FIG. 8 arearranged in offset fashion with respect to some of the columns to whichthey are adjacent. A myriad of column arrangements are possible, fromwell-organized arrangements of the columns to a random columnararrangement. It is preferred that the columns be arranged so that thetotal volume of gel cushioning media 802 within the volume of spaceoccupied by the cushioning element 801 is minimized. This results in alightweight cushion. To that end, the columns 803 may be arranged inclose proximity to each other in order to minimize the thickness of thecolumn walls 804. This will result in a lighter cushion and a cushionthat will yield to a greater extent under a cushioned object of a givenweight than a similar cushion with thicker column walls 804.

Referring to FIG. 9, an alternative cushioning element 901 is depictedwith cushioning media 902, columns 903, column walls 904 and outerperiphery 905 of the cushioning element 901 being shown. The columns 902depicted are round in a cross section taken orthogonal to theirlongitudinal axes. The reader should note that it may be desirable toinclude a container or side walls which will contain the outer periphery905 of the cushioning element. For example, in FIG. 9, a rectangular boxwith interior dimensions just slightly larger than the exteriordimensions of the cushioning element 901 could be employed. Or, as shownin FIG. 1, the side walls of the cover 204 could be rigid, such as bythe use of plastic inserts. The effect of rigid side walls or a rigidcontainer for a cushioning element is that when a cushioned object isplaced on the cushioning element, the cushioning media will not bepermitted to bulge outward at the cushioning element outer periphery. Bypreventing such outward bulging, greater cushion stability is achievedand a more direct (i.e. in a direction parallel to the longitudinal axisof a column, which in most of the figures, such as FIG. 3, is assumed tobe in the direction of the Earth's gravity but which may not always beso) movement or descent of the cushioned object into the cushion isachieved. A direct movement or descent of a cushioned object into thecushion (i.e. parallel to the longitudinal axes of the columns) isdesired because the column walls are configured to absorb weight andcushion the cushioned object, or, if the load under a protuberance getshigh enough, by buckling of the columns. If a cushioned object travels asubstantial distance sideways in the cushion, the hollow portion of thecolumns may be eliminated by opposing column walls collapsing to meeteach other rather than either substantially compressing the cushioningmedia or by buckling as depicted in FIGS. 13 and 14. This would notprovide the desired cushioning effect as it would result in collapsedcolumns within the cushion (rather than buckled columns), and thecushion would have little more cushioning effect than a solid block ofthe cushioning media without the columns.

Referring to FIG. 10, an alternative embodiment of the invented cushion1001 is depicted. The cushion 1001 includes gel cushioning media 1002 inthe form of an outer cushion periphery 1003, and column walls 1004 whichform triangular hollow columns 1005. The reader should note that thecolumns of the various figures are merely illustrative, and in practice,the columns could be triangular, rectangular, square, pentagonal,hexagonal, heptagonal, octagonal, round, oval, n-sided or any othershape in a cross section taken orthogonal to the longitudinal axis of acolumn. The periphery of the cushioning element may also be triangular,rectangular, square, pentagonal, hexagonal, heptagonal, octagonal,round, oval, heart-shaped, kidney-shaped, elliptical, oval, egg-shaped,n-sided or any other shape.

FIG. 11 depicts a column 1101 of the invention including column walls1102 and 1103 and column interior 1104. The column 1101 has alongitudinal axis 1105 which is preferred to be oriented in the inventedcushion parallel to the direction of the longitudinal axis of a columnwhich should be the direction that the cushioned object sinks into thecushion. Thus, the column top 1106 is at the side of the cushion thatcontacts the cushioned object, and the column bottom 1107 is at the sideof the cushion that typically faces the ground and will rest on somesort of a base. Another way of describing this with respect to thelongitudinal axis of each column is that the column top is at one end ofthe longitudinal axis of a column and the column bottom is at the otherend of the longitudinal axis of a column. When an object to be cushionedis placed onto a cushion which contains many such columns 1101, such asis shown in FIG. 3, a depressive force 1108 is applied to the cushionand to the column 1101 by the cushioned object. Because the cushion isexpected to rest on some type of supporting surface, such as a base, areaction force 1109 is provided by the supporting surface. The cushion,including the column 1101, yields under the weight of the cushionedobject. This yielding is a result of compression of the cushioning mediaand, if the load under a protruding portion of the cushioned object ishigh enough, by buckling or partial buckling of the columns 1101. FromFIG. 11, it can be seen that the depicted column 1101 buckles becausethe flexible cushion walls 1102 and 1103 buckle outward around theperiphery of the column, as depicted by cross-sectional points 1110 and1111. In other words, the column walls buckle radially outwardorthogonally from the longitudinal axis of the column. This permits thecolumn 1101 to decrease in total length along its longitudinal axis 1108and thereby conform to the shape of protuberances on a cushioned object.Since buckled columns carry comparatively little load, this results in acushion that avoids pressure peaks on the cushioned object.

FIG. 12 depicts a column 1201 of the invention including column walls1202 and 1203 and column interior 1204. The column 1201 has alongitudinal axis 1205 which is preferred to be oriented in the inventedcushion parallel to the direction of movement of a cushioned objectsinking into the cushion. Thus, the column top end 1206 is at the sideof the cushion that contacts the cushioned object, and the column bottomend 1207 is at the side of the cushion that typically will rest on somesort of a base. When an object to be cushioned is placed against acushion which contains numerous columns 1201, such as is shown in FIG.3, a depressive force 1208 is applied to the cushion and to the column1201 by the cushioned object. Because the cushion is expected to rest onsome type of supporting surface, such as a base, a reaction force 1209is provided by the supporting surface. The cushion, including the column1201, yields under the weight of the cushioned object. This yielding isa result of compression of the cushioning media and, if the load under aprotruding portion of the cushioned object is high enough, by bucklingor partial buckling of the columns. From FIG. 12, it can be seen thatthe depicted column 1201 buckles because the flexible cushion wall 1202buckles outward from the column center or orthogonal away from thelongitudinal axis of the column at point 1210, while cushion wall 1203buckles inward toward the column center or orthogonal toward thelongitudinal axis of the column at points 1211. This buckling actioncauses the column 1201 to decrease in total length along itslongitudinal axis 1208 and thereby conform to the shape of protuberanceson a cushioned object. Point 1210 is depicted buckling outward (awayfrom the center of the column) and point 1211 is depicted as bucklinginward (toward the center of the column). Alternatively, both points1210 and 1211 could buckle inward toward the center of the column orboth could buckle outward. Since buckled columns carry comparativelylittle load, this results in a cushion that avoids pressure peaks on thecushioned object. Buckling of a column permits the column to decrease intotal length along its longitudinal axis and thereby conform to theshape of protuberances on a cushioned object. This results in a cushionthat avoids pressure peaks on the cushioned object. It should be notedby the reader that the columns 1101 and 1201 depicted in FIGS. 11 and 12are hollow columns which have interiors completely open to theatmosphere and which permit air to travel through the columns to enhanceventilation under the cushioned object. It is also of note that thecolumn 1201 of FIG. 12 has column walls 1202 and 1203 that includefenestrations 1210 (which may be holes or apertures in the column walls)that permit the flow of air between adjacent columns, providing anenhanced ventilation effect. Fenestrations are also useful for reducingthe weight of the cushioning element. The greater the size and/or numberof fenstrations in column walls, the less the cushion weighs. Thefenestrations or holes 1210 in the column walls could be formed bypunching or drilling, or they could be formed during molding of thecushioning element.

FIG. 13 depicts an alternative column 1301 of the invention includingcolumn walls 1302 and 1303 and a column interior 1304. The column 1301has a longitudinal axis 1305 which, in the invented cushion, ispreferably oriented parallel to the direction in which the cushionedobject is expected to sink into the cushion. Thus, the column top end1306 is at the side of the cushion that contacts the cushioned object,and the column bottom end 1307 is at the side of the cushion thattypically faces some sort of a base. When an object to be cushioned isplaced onto a cushion which contains column 1301, such as is shown inFIG. 3, a depressive force 1308 is applied to the cushion and to thecolumn 1301 by the cushioned object. Because the cushion is expected torest on some type of supporting surface, such as a base, a reactionforce 1309 is provided by the supporting surface. The cushion, includingthe column 1301, yields under the weight of the cushioned object. Thisyielding is a result of compression of the cushioning media and, if theload under a protruding portion of the cushioned object is high enough,by buckling or partial buckling of the columns. From FIG. 13, it can beseen that the depicted column 1301 buckles because the flexible cushionwalls 1302 and 1303 buckle outward from the column center or orthogonalaway from the longitudinal axis 1305 of the column at points 1311 and1310. This buckling action allows the column 1301 to decrease in totallength along its longitudinal axis 1305 and thereby conform to the shapeof protuberances on a cushioned object.

In the embodiment depicted, the column 1301 is a sealed columncontaining air or an inert gas within its interior 1304. Thus, as thecolumn 1301 decreases in length along its longitudinal axis, the gaswithin the column interior 1304 tends to support the column top end 1306and resist the downward movement of the cushioned object. This yields afirmer cushion. Alternatively, open or closed cell (or other) foam orfluid cushioning media could be provided within the interior of thecolumns or within some of them in order to increase the firmness of thecushion.

FIG. 14 depicts an alternative embodiment of the column of theinvention. The column 1401 depicted has column walls 1402 and 1403 and acolumn interior 1404. The column interior 1404 is open at column top end1405 and at column bottom end 1406 to permit air to pass through thecolumn 1401. Column 1401 has walls 1402 and 1403 which are thicker attheir bottom end 1406 than at their top end 1405, imparting cushionswhich include such columns with a soft cushioning effect when cushioningan object that sinks into the cushion to only a shallow depth, butprogressively providing firmer cushioning the deeper the cushionedobject sinks. This configuration of column 1401 permits the constructionof a cushion which accommodates cushioned objects of a very wide varietyof weight ranges. Alternatively, the column walls could be thicker atthe top than at the bottom, the column walls could be stepped, or thecolumn walls could have annular or helical grooves in them to facilitatebuckling under the load of a cushioned object. Additionally, the columninterior could be of a greater interior dimension orthogonal to itslongitudinal axis at one end than at the other. Or the columns could beof varying dimension and shape along their longitudinal axes.

FIG. 15 depicts a cross section of a cushioning element usingalternating stepped columns. The cushioning element 1501 has a pluralityof columns 1502 each having a longitudinal axis 1503, a column top 1504and a column bottom 1505. The column top 1504 and column bottom 1505 areopen in the embodiment depicted, and the column interior or columnpassage 1506 is unrestricted to permit air flow through the column 1502.The column 1502 depicted has side walls 1507 and 1508, each of which hasthree distinct steps 1509, 1510 and 1511. The columns are arranged sothat the internal taper of a column due to the step on its walls isopposite to the taper of the next adjacent column. This type ofcushioning element could be made using a mold similar to that depictedin FIG. 4.

FIG. 16 depicts an alternative embodiment of a cushioning element 1601.The cushioning element 1601 has a plurality of columns 1602, 1603 and1604, each having a column interior 1605, 1606 and 1607, and columnwalls 1608, 1609, 1610 and 1611. The column walls are made fromcushioning media, such as the preferred soft gel. In the embodiment ofthe invented cushioning element 1601 depicted, the cushioning media 1612has trapped within it a plurality of gas bubbles 1613, 1614 and 1615.When the preferred soft gel cushioning medium is used, since the gel isnot flowable at the temperatures to which the cushion is expected to beexposed during use, the bubbles remain trapped within the cushioningmedium. The use of bubbles within the cushioning medium reduces theweight of the cushion and softens the cushion to a degree which mightnot otherwise be available. Bubbles may be introduced into thecushioning medium by injecting air, another appropriate gas, or vaporinto the cushioning medium before manufacturing the cushioning element,by vigorously stirring the heated, flowable cushioning medium before itis formed into the shape of a cushion, or by utilizing a cushioningmedium of a composition that creates gas or boils at the temperatures towhich it is subjected during the manufacture of a cushioning element.Blowing agents, some of the uses of which are described in detail belowin connection with the disclosure of the preferred gel material, arealso useful for introducing gas bubbles into the cushioning medium.Microspheres, which are also discussed in greater detail below, are alsouseful for introducing gas pockets into the cushioning medium.

FIG. 17 depicts an embodiment of the invented cushioning element whichhas cushioning medium, solid exterior walls 1703 and 1704, a pluralityof columns 1705 and column walls 1706 forming the columns. Note thatalthough FIG. 17 shows a cushioning element 1701 with solid walls 1703and 1704, it is possible to make a cushioning element 1701 that hascolumns on its outer walls. The cushioning element is disposed within anoptional cover 1707. A container 1708 with relatively stiff or rigidwalls 1709 and 1710 of approximately the same size and shape as thecushioning element walls 1703 and 1704 is shown. The container 1708 hasa bottom or base 1711 on which the cushioning element is expected torest. The container 1708 walls 1709 and 1710 serve to restrict theoutward movement of the cushioning element 1701 when a cushioned objectis placed on it. When the preferred soft gel is used as a cushioningmedium, the cushioning element 1701 would tend to be displaced by theobject being cushioned were the side walls 1709 and 1710 of thecontainer 1711 not provided. In lieu of a container, any type ofappropriate restraining means may be used to prevent side displacementof the cushioning element in response to the deforming force of acushioned object. For example, individual plastic plates could be placedagainst the side walls 1703 and 1704 of the cushioning element 1701.Those plates could be held in place with any appropriate holder, such asthe cover 1707. As another example, an appropriate strap or girdle couldbe wrapped around all exterior side walls 1703 and 1704 of thecushioning element 1701. Such a strap or girdle would serve to restrainthe cushioning element 1701 against radial outward displacement inresponse to a cushioned object resting on the cushioning element.

FIG. 18 depicts an alternative embodiment of a cushion 1801 thatincludes a cushioning element 1802 and a cover 1803. The cushioningelement 1802 has side walls 1808 and 1809 about its periphery, the sidewalls 1808 and 1809 in this embodiment being generally parallel with thelongitudinal axis 1810 of a hollow column 1811 of the cushioning element1802. A gap 1806 exists between the cover 1803 and the side wall 1809 ofthe cushioning element. This gap 1806 accommodates the insertion of astiff or rigid reinforcing side wall support 1804 which may be made of asuitable material such as plastic, wood, metal or composite materialsuch as resin and a reinforcing fiber. Similarly, gap 1807 between sidewall 1808 and the cover 1803 may have side wall support 1805 insertedinto it. The side wall supports are configured to restrict thecushioning element from being substantially displaced in an outward orradial direction (a direction orthogonal to the longitudinal axis of oneof the columns of the cushioning element) so that the cushioningelement's columns will buckle to accommodate the shape of a cushionedobject, rather than permitting the cushioning element to squirm out fromunder the cushioned object.

FIG. 19 depicts an alternative embodiment of a cushioning element 1901including square columns 1908. The cushioning element has outer sidewalls 1902 and 1903 about its periphery. The reader should note thatalthough the outer periphery of the cushioning element in FIG. 19 isdepicted as rectangular, the outer periphery could be of any desiredconfiguration, such as triangular, square, pentagonal, hexagonal,heptagonal, octagonal, any n-sided polygon shape, round, oval,elliptical, heart-shaped, kidney-shaped, quarter moon shaped, n-sidedpolygonal where n is an integer, or of any other desired shape. The sidewalls 1902 and 1903 of the cushioning element 1901 have a peripheralstrap or girdle 1904 about them. The girdle 1904 has reinforcing sidewalls 1905 and 1906 which reinforce the structural stability of sidewalls 1902 and 1903 respectively of the cushioning element 1901. Theembodiment of the girdle 1904 depicted in FIG. 19 has a fasteningmechanism 1907 so that it may be fastened about the periphery of thecushioning element 1901 much as a person puts on a belt. The girdle 1904serves to confine the cushioning element 1901 so that when a cushionedobject is placed on the cushioning element 1901, the cushioning elementwill not tend to squirm out from beneath the girdle 1904. Thus, thecushioning element 1901 will tend to yield and conform to the cushionedobject as needed by having its cushioning medium compress and itscolumns buckle.

FIG. 20 depicts an alternative embodiment of a cushioning element 2001.The cushioning element 2001 includes cushioning medium 2002 such as thepreferred gel formed into column walls 2003 and 2004 to form a column2005. The column 2005 depicted has a sealed column top 2006 and a sealedcolumn bottom 2007 in order to contain a column filler 2008. The columnfiller 2008 could be open or closed cell foam, any known fluidcushioning medium such as lubricated spherical objects, or any otherdesired column filler. The cushioning element 2001 depicted has anadvantage of greater firmness compared to similar cushioning elementswhich either omit the sealed column top and column bottom or which omitthe column filler.

FIG. 21 depicts an alternative embodiment of a cushioning element 2101of the invention. The cushioning element 2101 has cushioning medium 2102formed into column walls 2103 and 2104. The column walls 2103 and 2104form a column interior 2105. The column 2106 has an open column top 2107and a closed column bottom 2108. In the embodiment depicted, the column2107 has a firmness protrusion 2109 protruding into the column interior2105 from the column bottom 2108. The firmness protrusion 2109 depictedis wedge or cone shaped, but a firmness protrusion could be of andesired shape, such as cylindrical, square, or otherwise in crosssection along its longitudinal axis. The purpose of the firmnessprotrusion 2109 is to provide additional support within a buckled columnfor the portion of a cushioned object that is causing the buckling. Whena column of this embodiment of the invention buckles, the cushioningelement will readily yield until the cushioned object begins to compressthe firmness protrusion. At that point, further movement of thecushioned object into the cushion is slowed, as the cushioning medium ofthe firmness support needs to be compressed or the firmness supportitself needs to be caused to buckle in order to achieve further movementof the cushioned object into the cushioning medium.

Referring now to FIG. 22, in another embodiment of the cushion, multipleindividual cushioning elements 2201a, 2201b, 2201c, etc. are providedwithin a single cushion 2200. In such embodiments, the cushions of thepresent invention are positioned side-to-side, with or without othermaterials between the individual cushions, and with or withoutconnecting the individual cushions to one another. For example,sixty-four cushions, each having a thickness of four inches, and foursides each two inches in length, can be placed in an eight-by-eightarrangement to form a four inch thick square cushion having sixteen inchsides. Such cushions may be useful where different cushioningcharacteristics are desired on different portions of a cushion.Different cushioning characteristics are achieved through varying thematerials and/or configurations of the individual cushions.

With reference to FIGS. 23a, 23b, 23c and 23d, another embodiment of acushion 2301 according to the present invention is shown. Embodiment2301 includes a first cushioning medium 2302 which forms a cover and asecond cushioning medium 2303 which fills the cover. First cushioningmedium 2302 is preferably the preferred elastomeric gel material, whichis disclosed in detail below. Preferably, second cushioning medium 2303is the visco-elastomeric material that is disclosed in detail below.

Embodiment 2301 also includes columns 2304, column walls 2305 and anouter periphery 2306. Columns 2304 are formed through cover 2302 andlined with cushioning medium 2302. With reference to FIGS. 23a and 23b,where two adjacent columns 2304a and 2304b are separated only by a thincolumn wall 2305a (e.g., a column wall having a thickness of only about0.1 inch or less), the column wall is preferably made from cushioningmedium 2302. Where two adjacent columns 2304c and 2304d are separated bya thicker column wall 2305c, the column wall preferably includes a cover2302 of the first cushioning medium and is filled with second cushioningmedium 2303.

The use of multiple cushioning media in cushion 2301 facilitatestailoring of the rebound, pressure absorption, and flow characteristicsof the cushion. Compressibility of cushion 2301 also depends upon theamount of spacing between columns and the formulations of the firstsecond cushioning media 2302 and 2303, respectively.

FIGS. 24a and 24b illustrate another embodiment of the cushioningelement 2401 according to the present invention. Referring to FIG. 24b,embodiment 2401 includes a cushioning medium 2402, a coating 2403adhered to the cushioning medium, columns 2404, column walls 2405 thatseparate the columns, and an outer periphery 2406. Preferably,cushioning medium 2402 of embodiment 2401 is tacky, which facilitatesadhesion of coating 2403 thereto. A preferred cushioning medium 2402 foruse in embodiment 2401 is the preferred visco-elastomeric gel material,which is disclosed in detail below. Coating 2403 is preferably aparticulate material, including without limitation lint, short fabricthreads, talc, ground cork, microspheres, and others. However, coating2403 may me made from any material that will form a thin, pliable layerover cushioning medium 2402, including but not limited to fabrics,stretchable fabrics, long fibers, papers, films, and others.

FIGS. 25a, 25b, 25c, 25d, 25e and 25f show another embodiment of acushioning element 2501 according to the present invention. Embodiment2501 includes cushioning medium 2502, a first set of columns 2503 whichare oriented along a first axis x, a second set of columns 2504 whichare oriented along a second axis y, a third set of columns 2505 whichare oriented along a third axis z, column walls 2506 located between thecolumns, and an outer periphery 2507. Preferably, axis x isperpendicular to both axis y and axis z and axis y is perpendicular toaxis z. Columns 2503 and 2504, 2503 and 2505, and/or 2504 and 2505 mayintersect each other. FIGS. 25a, 25b and 25c illustrate a cushion 2501awherein columns 2503a intersect columns 2504 and columns 2503b intersectcolumns 2505. FIGS. 25d, 25e and 25f depict a cushion 2501b wherein eachof columns 2503 intersect both columns 2504 and columns 2505.Alternatively, none of the columns may intersect any other columns.Other variations of intersection and/or non-intersecting columns arealso within the scope of the present invention.

The spacing and pattern with which each set of columns is positioneddetermines the total volume of cushioning medium 2502 within the volumeof space occupied by the cushioning element 2501. As the volume ofcushioning medium 2502 within the volume of space occupied by thecushioning element 2501 decreases, the cushion becomes lighter andeasier to compress. Thus, the spacing and pattern of each set of columnsmay be varied to provide a cushion of desired weight andcompressibility. Cushioning elements which have only two sets of columnsor more than three sets of columns are also within the scope ofembodiment 2501.

With reference to FIG. 26, another embodiment of cushioning element 2601is shown which includes a first set of columns 2603 which are orientedalong a first axis x, a second set of columns 2604 which are orientedalong a second axis y, and a third set of columns 2605 which areoriented along a third axis z. As can be seen in FIG. 26, columns 2603,2604 and 2605 are preferably thin. Column walls 2606, which are madefrom a cushioning medium 2602, surround each of the columns. The cushion2601 shape is defined in part by an outer periphery 2607. Preferably,axis x is perpendicular to both axis y and axis z and axis y isperpendicular to axis z. Similar to the cushion of embodiment 2501,columns 2603, 2604 and 2605 may or may not intersect any other columns.Likewise, the spacing between adjacent columns and the arrangement ofeach of the columns determine the total volume of cushioning medium 2602within the volume of space occupied by the cushioning element 2601. Asthe volume of cushioning medium 2602 within the volume of space occupiedby the cushioning element 2601 decreases, the cushion becomes lighterand easier to compress. Thus, the spacing and arrangement of columns maybe varied to provide a cushion of desired weight and compressibility.Cushions with only two sets of columns or more than three sets ofcolumns are also within the scope of embodiment 2601.

Referring now to FIGS. 27a, 27b and 27c, another embodiment of acushioning element 2701 according to the present invention is shown.Embodiment 2701 includes cushioning medium 2702, a first set of columns2703 which are oriented along a first axis x, a second set of columns2704 which are oriented along a second axis y, a third set of columns2705 which are oriented along a third axis z, column walls 2706 locatedbetween the columns, cavities 2707 formed within the column walls and anouter periphery 2708. Preferably, axis x is perpendicular to both axis yand axis z and axis y is perpendicular to axis z. Columns 2703 and 2704,2703 and 2705, and/or 2704 and 2705 may intersect each other, as inembodiments 2501 and 2601. Alternatively, none of the columns mayintersect any other column. The spacing and pattern with which each setof columns is positioned and the number of cavities 2706 formed withinthe column walls 2707 determine the total volume of cushioning medium2702 within the volume of space occupied by the cushioning element 2701.As the volume of cushioning medium 2702 within the volume of spaceoccupied by the cushioning element 2701 decreases, the cushion becomeslighter and easier to compress. Thus, the spacing and pattern of eachset of columns may be varied to provide a cushion of desired weight andcompressibility. Similarly, the size and spacing of the cavities 2706within the column walls 2707 may also be varied to provide a cushion ofdesired weight and compressibility. Cushioning elements which have onlytwo sets of columns are also within the scope of embodiment 2701.

FIG. 28 illustrates yet another embodiment of a cushioning element 2801of the present invention, which has a contoured upper surface. Thecushion 2801 shown in FIG. 28 has columns 2803 and 2804 of differentheights and column walls 2805 and 2806 of different heights. However, acontoured cushion according to embodiment 2801 could include columns andcolumn walls having any number of different heights. Embodiment 2801also includes cushioning medium 2802 and an outer periphery 2807. Thevariability of column and column wall height in embodiment 2801 impartsthe cushion with areas having different compressibility and firmnesscharacteristics.

As seen in FIG. 28, cushion 2801 has two distinct levels of columns. Theadjacent longer columns 2803 are grouped together, referred to as a setof isolated columns 2808. The shorter columns 2804, which are locatedbetween sets 2808, tie cushion 2801 together and form a cushion base2809.

As an example of the use of cushion 2801, a cushioned object which comesinto contact with the top surface thereof will first compress columns2803, causing the column walls 2805 to buckle. The free area betweenisolated column sets 2808 enhances the bucklability of columns 2803. Inother words, columns 2803 buckle more easily than would columns of thesame size, separated by column walls of the same thickness and made fromthe same material in a cushion having columns of only one generalheight. If the load of the cushioned object causes complete buckling ofcolumns 2803, columns 2804, which have a greater resistance to bucklingthan the long columns, provide a secondary cushioning effect, which ismore like that of a cushion with columns of one general length.

Referring now to FIG. 29, a cushion 2901 is shown which includes acushioning medium 2902, columns 2903, column walls 2904, and an outerperiphery 2905. Cushioning medium includes a plurality of cells 2906a,2906b, 2906c, etc. which are filled with gas or another cushioningmedium. The cushion 2901 depicted in FIG. 29 has open cells 2906.Alternatively, cushion 2901 may have only closed cells or a combinationof open and closed cells. Cells 2906a, 2906b, 2906c, etc. may be of anysize and may be dispersed throughout cushioning medium at any density orconcentration that will provide the desired cushioning and weightcharacteristics.

Referring now to FIGS. 30a and 30b, alternative embodiments of thecushions 3001 and 3001' of the present invention which have light weightcolumn walls 3004 and 3004', respectively, are shown. Cushions 3001 and3001' also include a cushioning medium 3002 and 3002', columns 3003 and3003' and an outer periphery 3005 and 3005', respectively. Column walls3004 and 3004' each include a matrix 3006 and 3006', respectively,within which are located several voids 3007a, 3007b, 3007c, etc. and3007a', 3007b', 3007c', etc. and 3008a, 3008b, etc., respectively.Matrix 3006 is made from cushioning medium 3002, 3002'. Voids 3007,3007', 3008 are hollow areas formed within matrix 3006 which lightencolumn walls 3004, 3004'. Preferably, voids 3007, 3007' are filled withgas or any other substance which has a density (i.e., specific gravity)less than that of cushioning medium 3002, 3002'. More preferably, voids3007, 3007' are open celled (i.e., continuous with the outer surface ofcushion 3001, 3001' and exposed to the atmosphere).

FIG. 30a shows cushion 3001, the column walls 3004 of which include amatrix 3006 which forms voids 3007a, 3007b, 3007c, etc. having amulti-sided irregular shape. Column walls which have matrices and pitsof other configurations are also within the scope of the cushioningelements of the present invention. Embodiment 3001 is preferably formedby removal or destruction of volume occupying objects which aredispersed throughout the cushioning medium as cushion 3001 is formed.This process is described in greater detail in the U.S. ProvisionalPatent Application filed on the same date as this patent application,entitled "SUBSTANCE REMOVAL METHOD FOR FORMING CELLS IN A MATERIAL" byTony M. Pearce.

FIG. 30b shows cushion 3001' having a matrix 3006' formed from randomlyoriented short tubes 3009a, 3009b, 3009c, etc. which forms voids 3007'and 3008. Voids 3007a', 3007b', 3007c', etc. are formed within shorttubes 3009a, 3009b, 3009c, etc. and are generally cylindrical in shape.Matrix 3006' also includes irregularly shaped secondary voids 3008a,3008b, 3008c, etc. which are formed by the exterior surfaces of tubes3009 between adjacent tubes.

It is contemplated in the invention that the hollow portion of thecolumn will typically be of uniform cross section throughout its length,but this is not necessary for all embodiments of the invention. Forexample, in a column having a circular cross section orthogonal to itslongitudinal axis, the diameter of the circle could increase along itslength, and adjacent columns could correspondingly decrease along theirlength (i.e. the columns would be formed as opposing cones). As anotherexample, the column walls could all thicken from one cushion surface toanother to facilitate the use of tapered cores (which create the hollowportion of the columns) in the manufacturing tool, which taperingfacilitates the removal of the cores from the gel.

It is also preferred that the columns of the preferred cushioningelement be open at their top and bottom. However, the columns can bebonded to or integral with a face sheet on the top or bottom or both,over all or a portion of the cushion. Or the columns can be interruptedby a sheet of gel or other material at their midsection which is like aface sheet except that it cuts through the interior of a cushioningelement.

In the preferred embodiment of the cushioning element the column wallsare not perforated. However, perforated walls and/or face sheets arewithin the scope of this invention. The perforation size and density canbe varied by design to control column stiffness, buckling resistance,and weight, as well as to enhance air circulation.

It is also preferred that the wall thickness of the columns beapproximately equal throughout the cushioning element for uniformity,but in special applications of the invented cushion, wall thickness maybe varied to facilitate manufacturing or to account for differingexpected weight loads across the cushion or for other reasons.

Typical cushions in the art are ordinarily one piece, but the inventedcushion can be constructed from more than one discontinuous cushioningelement of the invention. For example, three one-inch thick cushions ofthis invention can be stacked to make a three-inch thick cushion of thisinvention, with or without other materials between the layers, and withor without connecting the three layers to one another.

The cushioning element of this invention can be used alone or with acover. A cover can be desirable when used to cushion a human body tomask the small pressure peaks at the edges of the column walls. This isnot necessary if the gel used is soft enough to eliminate these effects,but may be desirable if firmer gels are used. Covers can also bedesirable to keep the gel (which can tend to be sticky) clean. If used,a cover should be pliable or stretchable so as not to overly reduce thegross cushioning effects of the columns compressing and/or buckling. Thepreferred cover would also permit air to pass through it to facilitateair circulation under the cushioned object.

While it is envisioned that the immediate application of the inventedcushion is to cushion human beings (e.g., seat cushions, mattresses,wheelchairs cushions, stadium seats, operating table pads, etc.),Applicant also anticipates that other objects, including withoutlimitation, animals (e.g. between a saddle and a horse), manufacturedproducts (e.g., padding between a manufactured product and a shippingcontainer), and other objects may also be efficiently cushioned usingthe invention.

Preferably, the columns in the invented cushion are oriented with theirlongitudinal axis generally parallel to the direction of gravity so thatthey will buckle under load from a cushioned object rather than collapsefrom side pressure. It is also preferred that some type of wall orreinforcement be provided about the periphery of the cushioning elementin order to add stability to the cushioning element and in order toensure that the buckling occurs in order to decrease column length undera cushioned object.

The invented cushioning element may be described as a gelatinouselastomeric or gelatinous visco-elastomeric material (i.e. gel)configured as laterally connected hollow vertical columns whichelastically sustain a load up to a limit, and then buckle beyond thatlimit. This produces localized buckling in a cushioning element beneatha cushioned object depending upon the force placed upon the cushioningelement in a particular location. As a result, protruding portions ofthe cushioned object can protrude into the cushion without beingsubjected to pressure peaks. As a result, the cushioning elementdistributes its supportive pressure evenly across the contact area ofthe cushioned object. This also maximizes the percentage of the surfacearea of the cushioned object that is in contact with the cushion.

In the preferred embodiments, each individual column wall can buckle,markedly reducing the load carried by that column and causing eachcolumn to be able to conform to protuberances of the cushioned object.Buckling may be described as the localized crumpling of a portion of acolumn, or the change in primary loading of a portion of a column fromcompression to bending. In designing structural columns, such asconcrete or steel columns for buildings or bridges, the designer seeksto avoid buckling because once a column has buckled, it carries far lessload than when not buckled. In the columns of this cushion, however,buckling works to advantage in accomplishing the objects of theinvention. The most protruding parts of the cushioned object cause theload on the columns beneath those protruding parts to have a higher thanaverage load as the object initially sinks into the cushion. This higherload causes the column walls immediately beneath the protruding portionof the cushioned object to buckle, which markedly reduces the load onthe protruding portion. The surrounding columns, which have not exceededthe buckling threshold, take up the load which is no longer carried bythe column(s) beneath the most protruding portion of the cushionedobject.

As an example of the desirability of the buckling provided by thecushioning element of the invention, consider the dynamics of a seatcushion. The area of a seated person which experiences the highest levelof discomfort when seated without a cushion (such as on a wooden bench)or on a foam cushion is the tissue that is compressed beneath the mostprotruding bones (typically the ischial tuberosities). When the inventedcushioning element is employed, the area beneath the protruding portionswill have columns that buckle, but the remainder of the cushioningelement should have columns (which are beneath the broad, fleshynon-bony portion of the person's posterior) which will withstand theload placed on them and not buckle. Since the broad fleshy area overwhich the pressure is substantially equal is approximately 95% of theportion of the person subjected to sitting pressure, and the areabeneath the ischial tuberosity is subjected to less than averagepressure due to the locally buckled gel columns (in approximately 5% ofthat area), the person is well supported and the cushion is verycomfortable to sit on.

As another example, the cushioning element of the invention is useful ina bed mattress. The shoulders and hips of a person lying on his/her sidewould buckle the columns in the cushioning element beneath them,allowing the load to be picked up in the less protruding areas of theperson's body such as the legs and abdomen. A major problem in prior artmattress cushions is that the shoulders and hips experience too muchpressure and the back is unsupported because the abdomen receives toolittle pressure. The cushion of this invention offers a solution to thisproblem by tending to equalize the pressure load through local bucklingunder protruding body parts.

The square columns of FIGS. 7 or 8 in the invented cushion are believedby Applicant to have the best balance between lateral stability(resistance to collapse from side loads) and light weight (which alsocorresponds to good air circulation and low thermal transfer). Someother types of columns, such those depicted in the other figures ormentioned elsewhere herein, have more cushioning media (typically gel)per cubic inch of cushion for a given level of cushioning support. Thus,the resulting cushions are heavier and have a higher rate of thermaltransfer. They are also more costly to manufacture due to the increasedamount of cushioning media required. However, columns with oval,circular or triangular cross sections are preferred for some cushioningapplications because they have a greater degree of lateral stabilitythan square or honeycomb columns since triangles form a braced structureand circles and ovals form structurally sound arches when consideredfrom a lateral perspective. Honeycomb columns such as those shown inFIGS. 2, 4, 5, 7, 8, 9 and 10 generally have the least gel per cubicinch of cushion for a given level of support, but have little lateralstability. However, they can be the preferred embodiment in anycushioning application which has need for lightest weight and does notrequire substantial lateral stability.

The cushions of this invention differ from prior art gel cushions inthat, while prior art gel cushions come in a variety of shapes, many areessentially a solid mass. When a cushioned object attempts to sink intoa prior art gel cushion, the cushion either will not allow the sinkingin because the non-contact portions of the cushion are constrained fromexpanding, or the cushion expands undesirably by pushing gel away fromthe most protruding parts of the cushioned object in a manner whichtends to increase the reactive force exerted by the gel against areas ofthe cushioned object which surround the protrusions. In the cushion ofthis invention, the gel has enough hollow space to allow sinking inwithout expanding the borders of the cushion, so the problem isalleviated.

Another problem with many prior art gel cushions is their weight. Forexample, a wheelchair cushion made of prior art gel with dimensions of18"×16"×3.5" would weigh 35-40 pounds, which is unacceptable to manywheelchair users. A cushion according to this invention having the samedimensions would weigh approximately seven pounds or less. To be anacceptable weight for wheelchairs, a typical prior art wheelchair gelcushion is made only 1" thick. To prevent bottoming out through such athin cushion, the makers increase the rigidity of the gel, whichdecreases the gel's semi-hydrostatic characteristics, ruining the gel'sability to equalize pressure. Thus, many thin gel cushions relievepressure no better than a foam cushion. The cushion of this inventioncan be the preferred full 3.5 inches thick needed to allow sinking infor a human user which is in turn needed to equalize pressure andincrease the surface area under pressure, while still being lightweight.

The cushions of this invention differ from prior art honeycomb cushionsin part in that gel is used instead of thermoplastic film orthermoplastic elastomer film. Also, a comparatively thick gel is usedfor the walls of the columns, as compared to very thin films made ofcomparatively much more rigid thermoplastic film or thermoplasticelastomer film. If thick walls were used in prior art honeycombcushions, the rigidity of available thermoplastics and availablethermoplastic elastomers would cause the cushion to be far too stiff fortypical applications. Also, the use of comparatively hard, thin wallsputs the cushioned object at increased risk. When the load on a priorart honeycomb cushion exceeds the load carrying capability of virtuallyall of the columns (i.e., they all buckle), the cushioned object bottomsout onto a relatively hard, rigid, thin pile of thermoplastic filmlayers. In that condition, the cushioned object is subjected topressures similar to the pressures it would experience with no cushionat all. The cushioned object is thus at risk of damaging pressures onits most protruding portions.

In comparison, if the same bottoming out occurs on the cushion of thisinvention, the most protruding portions of the cushioned object would bepressed into a pile of relatively thick, soft gel layers, which wouldadd up to typically 20% of the original thickness of the cushion. Thus,the risk of bottoming out is substantially lowered.

Another difference between prior art thermoplastic honeycomb cushionsand the cushion of this invention is that the configuration of theinvented cushion is not limited to honeycomb columns, but can takeadvantage of the varying properties offered by columns of virtually anycross sectional shape. The prior art thermoplastic honeycomb cushionsare so laterally unstable that at least one face sheet must be bondedacross the open cells. This restricts the air circulation, which is onlysomewhat restored if small perforations are made in the face sheet orcells. While face sheets and perforations are an option on the cushionsof this invention, the alternative cross sectional shapes of the columns(e.g., squares or triangles) make face sheets unnecessary due toincreased lateral stability and thus perforations are unnecessary sinceboth ends of the preferred configuration of the column are open to theatmosphere.

The maximum thickness of the walls of the columns of the cushion of thisinvention should be such that the bulk density of the cushion is lessthan 50% of the bulk density if the cushion were completely solid gel.Thus, at least 50% of the volume of space occupied by the inventedcushioning element is occupied by a gas such as air and the remainder isoccupied by gel. The minimum thickness of the walls of the columns iscontrolled by three factors: (1) manufacturability; (2) the amount ofgel needed for protection of the cushioned object in the event of allcolumns buckling; and (3) the ability to support the cushioned objectwithout buckling the majority of the columns. The preferred thicknesswould be such that the columns under the most protruding parts of thecushioned object are buckled, and the remaining columns are compressedin proportion to the degree of protrusion of the cushioned objectimmediately above them but are not buckled.

B. Cushion Materials

It is preferred that the cushioning media used to manufacture theinvented cushioning element be a soft gel. This assures that theinvented cushion will yield under a cushioned object by having bucklingcolumns and by the cushioning medium itself compressing under the weightof the cushioned object. The soft gel will provide additional cushioningand will accommodate uneven surfaces of the cushioned object.Nevertheless, firmer gels are also useful in the cushioning element ofthe invention, provided that the gel is soft enough to provideacceptable cushioning for the object in the event that all of thecolumns buckle. Since, with a given type of gel, there is typically acorrelation between softness and Young's modulus (stiffness)(i.e., asofter gel is less stiff), and since there is a correlation betweenYoung's modulus and the load carrying capability of a column beforebuckling, there is typically a need for firmer gels in cushions whichwill carry a higher load. However, there are other alternatives forincreasing a cushion's load carrying capability, such as increasing thecolumn wall thickness, so that the softness of the gel can be selectedfor its cushioning characteristics and not solely for its load bearingcharacteristics, particularly in cases where cushion weight is not afactor. Any gelatinous elastomer or gelatinous visco-elastomer with ahardness on the Shore A scale of less than about 15 is useful in thecushioning element of the present invention. Preferably, the cushioningmedium has a Shore A hardness of about 3 or less. More preferred arematerials which have a hardness of less than about 800 gram bloom. Suchmaterials are too soft to measure on the Shore A scale. Gram Bloom isdefined as the gram weight required to depress a gel a distance of fourmillimeters (4 mm) with a piston having a cross-sectional area of onesquare centimeter (1 cm²) at a temperature of about 23° C. The preferredgel is cohesive at the normal useable temperatures of a cushioningelement. The preferred gel will not escape from the cushioning elementif the cushioning element is punctured. The preferred gel has shapememory so that it tends to return to its original shape afterdeformation.

The cushioning media or preferred gel must also be strong enough towithstand the loads and deformations that are ordinarily expected duringthe use of a cushion. For a given type of gel, there is typically acorrelation between softness and strength (i.e., softer gels are not asstrong as harder gels).

Because of their high strength even in soft formulations, their lowcost, their ease of manufacture, the variety of manufacturing methodswhich can be used, and the wide range of Young's modulus which can beformulated while maintaining the hydrostatic characteristics of a gel,the gel formulations which follow are the most preferred gels to be usedin the cushions of this invention.

Applicant believes that the reader might benefit from a generalbackground discussion of the chemistry underlying the preferred gelsprior to reading about the preferred formulations of the preferred gels.

1. Chemistry of Plasticizer-Extended Elastomers

A basic discussion of the chemical principles underlying thecharacteristics and performance of plasticizer-extended elastomers isprovided below to orient the reader for the later discussion of theparticular chemical aspects of the preferred material for use in thecushions of the present invention.

The preferred gel cushioning medium is a composition primarily oftriblock copolymers and plasticizers, both of which are commonlyreferred to as hydrocarbons. Hydrocarbons are elements which are made upmainly of Carbon (C) and Hydrogen (H) atoms. Examples of hydrocarbonsinclude gasoline, oil, plastic and other petroleum derivatives.

Referring to FIG. 31a, it can be seen that a carbon atom 3110 typicallyhas four covalent bonding sites"". FIG. 31b shows a hydrogen atom 3112,which has only one covalent bonding site. With reference to FIG. 31c,which represents a four-carbon molecule called butane, a "covalent"bond, represented at 3116 as "-", is basically a very strong attractionbetween adjacent atoms. More specifically, a covalent bond is thelinkage of two atoms by the sharing of two electrons, one contributed byeach of the atoms. For example, the first carbon atom 3118 of a butanemolecule 3114 shares an electron with each of three hydrogen atoms 3120,3122 and 3124, represented as covalent bonds 3121, 3123 and 3125,respectively, accounting for three of carbon atom 3118's availableelectrons. The final electron is shared with the second carbon atom3126, forming covalent bond 3127. When atoms are covalently bound to oneanother, the atom-to-atom covalent bond combination makes up a moleculesuch as butane 3114. An understanding of hydrocarbons, the atoms thatmake hydrocarbons and the bonds that connect those atoms is importantbecause it provides a basis for understanding the structure andinteraction of each of the components of the preferred gel material.

As mentioned above, the preferred gel cushioning material utilizestriblock copolymers. With reference to FIGS. 32a and 32b, a triblockcopolymer is shown. Triblock copolymers 3210 are so named because theyeach have three blocks--two endblocks 3212 and 3214 and a midblock 3216.If it were possible to grasp the ends of a triblock copolymer moleculeand stretch them apart, each triblock copolymer would have a string-likeappearance (as in FIG. 32a), with an endblock being located at each endand the midblock between the two endblocks.

FIG. 33a depicts the preferred endblocks of the copolymer most preferredfor use in the preferred gel material, which are known asmonoalkenylarene polymers 3310. Breaking the term "monoalkenylarene"into its component parts is helpful in understanding the structure andfunction of the endblocks. "Aryl" refers to what is known as an aromaticring bonded to another hydrocarbon group. Referring now to FIG. 33b,benzene 3312, one type of aromatic ring, is made up of six carbonmolecules 3314, 3316, 3318, 3320, 3322 and 3324 bound together in aring-like formation. Due to the ring structure, each of the carbon atomsis bound to two adjacent carbon atoms. This is possible because eachcarbon atom has four bonding sites. In addition, each carbon atom C of abenzene molecule is bound to only one hydrogen atom H. The remainingbonding site on each carbon atom C is used up in a double covalent bond3326, 3327, which is referred to as a double bond. Because each carbonatom has only four bonding sites, double bonding in an aromatic ringoccurs between a first carbon and only one of the two adjacent carbons.Thus, single bonds 3116 and double bonds 3326 alternate around thebenzene molecule 3312. With reference to FIG. 33c, in an aryl group3328, one of the carbons 3330 is not bound to a hydrogen atom, whichfrees up a bonding site R for the aryl group to bond to an atom or groupother than a hydrogen atom.

Turning now to FIG. 33d, "alkenyl" 3332 refers to a hydrocarbon groupmade up of only carbon and hydrogen atoms, wherein at least one of thecarbon-to-carbon bonds is a double bond 3334 and the hydrocarbon groupis connected to another group of atoms R', where R' represents theremainder of the hydrocarbon molecule and can include a single hydrogenatom. Specifically, the "en" signifies that a double bond is presentbetween at least one pair of carbons. The "yl" means that thehydrocarbon is attached to another group of atoms. For example, FIG. 33eshows a two carbon group having a double bond between the carbons, whichis called ethenyl 3336. Similarly, FIG. 3f illustrates a three carbongroup having a double bond between two of the carbons, which is calledpropenyl 3338. Referring again to FIG. 33a, in a monoalkenylarene suchas styrene, a carbon 3340 with a free bonding site of an alkenyl group3332 is bonded to the aryl group 3328 at carbon atom 3330, which alsohas a free bonding site. In reference to FIG. 33c, aryl group 3328 ispart of a monoalkenylarene molecule when R is an alkenyl group. The"mono" of monoalkenylarene explains that only one alkenyl group isbonded to the aryl group.

The monoalkenylarene end blocks of a triblock copolymer are polymerized.Polymerization is the process whereby monomers are connected in achain-like fashion to form a polymer. FIG. 34a depicts a polymer 3410,which is basically a large chain-like molecule formed from manyrepeating smaller molecules, called monomers, M1, M2, M3, etc., that arebonded together. P and P' represent the ends of the polymer, which arealso made up of monomers FIG. 34b illustrates a monoalkenylarene endblock polymer 3414, which is a chain of monoalkenylarene molecules3416a, 3416b, 3416c, etc. The chain of FIG. 34b is spiral, or helical,in shape due to the bonding angles between styrene molecules. Prepresents an extension of the endblock polymer helix in one direction,while P' represents an extension of the endblock polymer helix in theopposite direction.

As FIG. 34c shows, monoalkenylarene molecules are attracted to oneanother by a force that is weaker than covalent bonding. The primaryweak attraction between monoalkenylarene molecules is known ashydrophobic attraction. An example of hydrophobic attraction is theattraction of oil droplets to each other when dispersed in water.Therefore, in its natural, relaxed state at room temperature, amonoalkenylarene polymer resembles a mass of entangled string 3414, asdepicted in FIG. 34d. The attraction of monoalkenylarene molecules toone another creates a tendency for the endblocks to remain in anentangled state. Similarly, different monoalkenylarene polymers areattracted to each other. The importance of this phenomenon will becomeapparent later in this discussion.

Like the end blocks of a triblock copolymer, the midblock is also apolymer. The preferred triblock copolymer for use in the elastomercomponent of the preferred cushioning medium includes is an aliphatichydrocarbon midblock polymer. Traditionally, "aliphatic" meant that ahydrocarbon was "fat like" in its chemical behavior. Referring to FIGS.35a through 35c, which, for simplicity, do not show the hydrogen atoms,an "aliphatic compound" is now defined as a hydrocarbon compound whichreacts like an alkane 3510 (a hydrocarbon molecule having only singlebonds between the carbon atoms), an alkene 3512 (a hydrocarbon moleculewherein at least one of the carbon-to-carbon bonds is a double bond)3514, an alkyne (a hydrocarbon molecule having a triple covalent bond3515 between at least one pair of carbon atoms), or a derivative of oneor a combination of the above.

Referring now to FIG. 35d, which omits the bound hydrogen atoms forsimplicity, aliphatic hydrocarbons known as conjugated dienes 3516 aredepicted. These are the preferred midblock monomers used in the triblockcopolymers of the preferred gel material for use in the presentinvention. A "diene" is a hydrocarbon molecule having two ("di") doublebonds ("ene"). "Conjugated" means that the double bonds 3518 and 3520are separated by only one single carbon-to-carbon bond 3522. Incomparison, FIG. 35e shows a hydrocarbon molecule having two doublecarbon-to-carbon bonds that are separated by two or more single bonds,3530, 3532, etc., which is referred to as an "isolated diene" 3524. Whendouble bonds are conjugated, they interact with each other, providinggreater stability to a hydrocarbon molecule than would the two doublebonds of an isolated diene.

FIGS. 36a through 36d illustrate examples of various monomers useful inthe midblock of the triblock copolymers preferred for use in theelastomer component of the preferred gel cushioning medium, includingmolecules (monomers) such as ethylene-butylene (EB) 3612,ethylene-propylene (EP) 3614, butadiene (B) 3616 (either hydrogenated ornon-hydrogenated) and isoprene (I) 3618 (either hydrogenated ornon-hydrogenated). The different structures of these molecules providethem with different physical characteristics, such as differingstrengths of covalent bonds between adjacent monomers. The variousstructures of monomer molecules also provides for different types ofinteraction between distant monomers on the same chain (e.g., when themidblock chain folds back on itself, distant monomers may be attractedto one another by a force weaker than covalent bonding, such ashydrophobic interaction, hydrophilic interaction, polar forces or VanderWaals forces).

Referring to FIGS. 36a and 36b, x, y and n each represent an integralnumber of each bracketed unit: "x" is the number of repeating ethylene(--CH2--CH2--) units, "y" is the number of repeating butylene (in FIG.36a) or propylene (in FIG. 36b) units, and "n" is the number ofrepeating poly(ethylene/butylene) units. Numerous configurations arepossible.

As shown in FIGS. 37a through 37d, the midblock may contain (i) only onetype of monomer, EB, EP, B or I or, as FIGS. 37e and 37f illustrate,(ii) a combination of monomer types EB and EP or B and I, providing forwide variability in the physical characteristics of different midblocksmade from different types or combination of types of monomers. Theinteraction of physical characteristics of each molecule (monomer andblock) determines the physical characteristics of the tangible, visiblematerial. In other words, the type or types of monomer molecules whichmake up the midblock polymer play a role in determining variouscharacteristics of the material of which the midblock is a part.

Attributes such as strength, elongation, elasticity or visco-elasticity,softness, tackiness and plasticizer retention are, in part, determinedby the type or types of midblock monomers. For example, referring againto FIG. 37a, the midblock polymer 3216 of a triblockcopolymer-containing material may be made up primarly or solely ofethylene-butylene monomers EB, which contribute to that material'sphysical character. With reference to FIG. 37e, in comparison to thematerial having a midblock made up solely of EB, a similartriblock-containing material, wherein the midblock polymer 3216 of thetriblocks are made up of a combination of butadiene B and isoprene Imonomers, may have greatly increased strength and elongation, similarelasticity or visco-elasticity and softness, reduced tackiness andreduced plasticizer bleed.

The monomer units of the midblock have an affinity for each other.However, the hydrophobic attraction of the midblock monomers for eachother is much weaker than the non-covalent attraction of the end blockmonomers for one another.

Referring now to FIG. 38a, which shows apolystyrene-poly(butadiene+isoprene)-polystyrene triblock copolymer, ina complete triblock copolymer 3810, each end 3812 and 3814 of midblockchain 3216 is covalently bound to an end block 3212 and 3214. P andP"represent the remainder of the endblock polymers 3212 and 3214respectively. P' represents the central portion of midblock polymer3216. Many billions of triblock copolymers combine to form a tangiblematerial. The triblock copolymers are held together by the high affinity(i.e., hydrophobic attraction) that monoalkenylarene molecules have forone another. In other words, as FIG. 38b illustrates, the endblocks ofeach triblock copolymer molecule, each of which resemble an entangledmass of string 3414, are attracted to the endblocks of another triblockcopolymer. When several endblocks are attracted to each other, they forman accretion of endblocks, called a domain or a glassy center 3816.Agglomeration of the endblocks occurs in a random fashion, which resultsin a three-dimensional network 3818 of triblocks, the midblock 3216 ofeach connecting endblocks 3212 and 3214 located at two different domains3816a and 3816b. In addition to holding the material together, thedomains of triblock copolymers also provide it with strength andrigidity.

Plasticizers are generally incorporated into a material to increase theworkability, pliability and flexibility of that material. Incorporationof plasticizers into a material is known as plasticization. Chemically,plasticizers are hydrocarbon molecules which associate with the materialinto which they are incorporated, as represented in FIG. 39a. In thepreferred gel material, plasticizer molecules 3910 associate with thetriblock copolymer 3210, and increase its workability, softness,elongation and elasticity or visco-elasticity. Depending upon the typeof plasticizer used, the plasticizer molecules associate with either theendblocks, the midblock, or both. In order to preserve the strength ofthe preferred gel materials, Applicant prefers the predominant use ofplasticizers 3910 which associate primarily with midblock polymer 3216of triblock copolymer 3818, rather than with the end blocks. However,plasticizers which associate with the end blocks may also be useful insome formulations of the preferred gel material. Plasticizers are alsodesired which associate with the principle thermoplastic polymercomponent of the gel material.

Chemists have proposed four general theories to explain the effects thatplasticizers have on certain materials. These theories are known as thelubricity theory, the gel theory, the mechanistic theory and the freevolume theory.

The lubricity theory, illustrated in FIGS. 39b through 39d, assumes thatthe rigidity of a material (i.e., its resistance to deformation) iscaused by intermolecular friction. Under this theory, plasticizermolecules 3910 lubricate the large molecules, facilitating movement ofthe large molecules over each other. See generally, Jacqueline I.Kroschwitz, ed., CONCISE ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING734-44, Plasticizers (1990), which is hereby incorporated by reference.In the case of triblock copolymers, lubrication of the endblocks shouldbe avoided since the endblock domains are responsible for holding thetriblock copolymers together and impart the material with strength(e.g., tensile strength during elongation). Thus, a plasticizer whichassociates with the midblocks is preferred. According to the lubricitytheory, when manipulative force is exerted on the material, plasticizer3910 facilitates movement of midblocks 3216 past each other. Id. at734-35. The arrows in FIGS. 39b, 39c and 39d represent the motion ofmidblocks 3216 with respect to each other. FIG. 39b represents adjacentmidblocks being pulled away from each other. FIG. 39c represents twomidblocks being forced side-to-side. FIG. 39d represents adjacentmidblocks being pulled across one another.

FIGS. 39e and 39f depict a second plasticization theory, the gel theory,which reasons that the resistance of amorphous polymers to deformationresults from an internal, three-dimensional honeycomb structure or gel.Loose attachments between adjacent polymer chains, which occur atintervals along the chains, called attachment points, form the gel.Closer attachment between adjacent chains creates a stiffer and morebrittle material. Plasticizers 3910 break, or solvate, the points ofattachment 3914 between polymer chains, loosening the structure of thematerial. Thus, plasticizers produce about the same effect on a materialas if there were fewer attachment points between polymer chains, makingthe material softer or less brittle. See Id. at 735. Since one of thepurposes of the preferred gel is to provide a material which does nothave significantly decreased tensile strength, which is provided byagglomeration of the endblocks, according to the gel theory plasticizer3910 should associate with midblocks 3216 rather than with theendblocks. Further, a plasticizer which associates with the midblockpolymers decreases the attachment of adjacent midblocks, which likelydecreases the rigidity while increasing the pliability, elongation andelasticity or visco-elasticity of the material. Similar to the lubricitytheory, under the gel theory, reduction of attachment points betweenadjacent midblocks facilitates movement of the midblocks past oneanother as force is applied to the material.

Referring now to FIG. 39g, the mechanistic theory of plasticizationassumes that different types of plasticizers 3910, 3912, etc. areattracted to polymer chains by forces of different magnitudes. Inaddition, the mechanistic theory supposes that, rather than attachpermanently, a plasticizer molecule attaches to a given attachment pointonly to be later dislodged and replaced by another plasticizer molecule.This continuous exchange of plasticizers 3910, 3912, etc., demonstratedby FIG. 39g as different stages connected by arrows which represent anequilibrium between each stage, is known as a dynamic equilibriumbetween solvation and desolvation of the attachment points betweenadjacent polymer chains. The number or fraction of attachment pointsaffected by a plasticizer depends upon various conditions, such asplasticizer concentration, temperature, and pressure. See Id.Accordingly, as applied to the preferred gel material for use in thisinvention, a large amount of plasticizer would be necessary to affectthe majority of midblock attachment points and thus provide the desiredamounts of rigidity, softness, pliability, elongation and elasticity orvisco-elasticity.

With reference to FIGS. 39h through 39j, the fourth plasticizationtheory, known as the free volume theory, assumes that there is nothingbut free space between molecules. As molecular motion increases (e.g.,due to heat), the free space between molecules increases. Thus, adisproportionate amount of that free volume is associated with the endsof the polymer chains. As FIGS. 39h through 39j demonstrate, free volumeis increased by using polymers with shorter chain lengths. For example,the black rectangles of FIG. 39h represent a material made up of longmidblock polymers 3216. The white areas around each black rectanglerepresent a constant width of free space around the molecule. In FIG.39i, a molecule 3916, which is smaller than midblock 3216, is added tothe material, creating more free space. In FIG. 39j, an even smallermolecule 3918 has been added to the material. The increase in free spacewithin the material is evident from the increased area of white space.The crux of the free volume theory is that the increase in free space orvolume allows the molecules to more easily move past one another. Inother words, the use of a small (or low molecular weight) plasticizerincreases the ability of the midblock polymer chains to move past eachother. While FIGS. 39h, 39i and 39j provide a fair representation of thefree volume theory, in reality, the increase in free space would be muchgreater than a two-dimensional drawing illustrates since molecules arethree-dimensional structures.

Similarly, the use of polymers with flexible side chains createadditional free volume around the molecule, which produces a similarplasticization-like effect, called internal plasticization. Applicantbelieves that incorporation of monomers into the midblock, which createflexible side chains thereon, including but not limited to isoprene(either hydrogenated or non-hydrogenated) and ethylene/propylenemonomers, creates internal plasticization. In comparision, the additionof an even smaller plasticizer molecule, described above, increases thefree space at a given location; this is external plasticization. Thesize and shape of plasticizing molecule and the nature of its atoms andgroups of atoms (i.e., nonpolar, polar, hydrogen bonding or not, anddense or light) determines the plasticizer's plasticizing ability on aspecific polymer. See Id.

With this general background in mind, Applicant will explain theformulation, chemical structure and performance of the preferred gelmaterial for use in the present invention.

2. Definitions

For the reader's convenience, Applicant has defined several terms whichare used throughout the description of the present gel. Additionally,other terms have been defined throughout the detailed description of thepreferred gel material.

a. Elasticity and Visco-Elasticity

When finite strains are imposed upon visco-elastic materials, such asthe preferred gel materials, the stress-strain relations are much morecomplicated than those ordinarily anticipated in accordance with theclassical theory of elasticity (Hooke's law) or the classical theory ofhydrodynamics (Newton's law). According to Hooke's law, stress is alwaysdirectly proportional to strain in small deformations but independent ofthe rate of strain or the strain history. Newton's law of hydrodynamics,which deals with the properties of viscous liquids, states that stressis always directly proportional to the rate of strain but independent ofthe strain itself.

"Elastic," as defined herein, refers to a characteristic of materialswhich return substantially to their original shape following deformationand the subsequent cessation of deforming force.

"Visco-," as defined herein, relates to both the rate of deformation andthe rate of reformation. In reference to deformation rate, the faster adeforming force is applied to a visco-elastic material, the stiffer itis. The rate of reformation of a visco-elastic material is slower thanthat of a truly elastic material.

Even if both strain and rate of strain are infinitesimal, avisco-elastic material may exhibit behavior that combines liquid-likeand solid-like characteristics. For example, materials that exhibitnot-quite-solid-like characteristics do not maintain a constantdeformation under constant stress but deform, or creep, gradually overtime. Under constant deformation, the stress required to hold avisco-elastic material in the deformed state gradually diminishes untilit reaches a relatively steady state. On the other hand, a visco-elasticmaterial that exhibits not-quite-liquid-like characteristics may, whileflowing under constant stress, store some of the energy input instead ofdissipating it all as heat. The stored energy may then cause thematerial to at least partially recover from its deformation, known aselastic recoil, when the stress is removed. When viscoelastic materialsare subjected to sinusoidally oscillating stress, the strain is neitherexactly in phase with the stress (as it would be for a perfectly elasticsolid) nor 90° out of phase (as it would be for a perfectly viscousliquid), but is somewhere in between. Visco-elastic materials store andrecover some of the deforming energy during each cycle, and dissipatesome of the energy as heat. If the strain and rate of strain on avisco-elastic material are infinitesimal, the behavior of that materialis linear viscoelastic and the ratio of stress to strain is a functionof time (or frequency) alone, not of stress magnitude. The gel materialpreferred for use in the present invention is elastic in nature.Visco-elastic materials are also useful in the cushions of the presentinvention.

b. Rebound Rate

"Rebound rate", as defined herein, is the amount of time it takes a oneinch long piece of material to rebound to within about five percent itsoriginal shape and size following the release of stress which elongatesthe material to a length of two inches. The preferred elastic (orelastomeric) gel material useful in the cushioning elements of thepresent invention has a rebound rate of less than about one second. Thepreferred visco-elastic (or visco-elastomeric) gel material useful inthe cushioning elements of the present invention has a rebound rate ofat least about one second. More preferably, the preferred visco-elasticgel has a rebound rate within the range of about one second to about tenminutes.

"Instantaneous Rebound," as defined herein, refers to a characteristicof a one inch long piece of an elastomeric material which returnssubstantially to its original size and shape in times of about onesecond or less following the release of stress which elongates thematerial to a length of two inches. "Elastomer," as used herein, refersto the gel materials that are useful in the cushioning element of thisinvention and which have instantaneous rebound.

"Delayed Rebound," as used herein, refers to a characteristic of thevisco-elastic materials preferred for use in the cushions of thisinvention which have a rebound rate of at least about one second. Morepreferably, the preferred visco-elastomeric material has a rebound ratewithin the range of about one second to about ten minutes."Visco-elastomer," as defined herein, refers to gel materials useful inthe invented cushions which exhibit delayed rebound characteristics.

c. Resins

The term "resin" is defined herein as a solid or semisolid fusible,organic substance that is usually transparent or translucent, is solublein organic solvent but not in water, is an electrical nonconductor, andincludes tackifiers. Resins are complex mixtures which associatetogether due to similar physical or chemical properties. Because oftheir complex nature, resins do not exhibit simple melting or boilingpoints.

"Resinous" as used herein refers to resins and resin-like materials.

"Resinous plasticizers" as used herein refers to plasticizers whichinclude a majority, by weight, of a resin or resins.

"Tackifier" as used herein refers to resins that add tack to theresulting mixture. The primary function of a tackifier is to add tack.The secondary functions of tackifiers include modification of both meltviscosity and melt temperature.

Tackifiers are normally low molecular weight and high glass transitiontemperature (T_(g)) materials, and are sometimes characterized as highlycondensed acrylic structures. The most commonly used tackifiers arerosin derivatives, terpene resins, and synthetic or naturally derivedpetroleum resins. A tackifier's effectiveness is largely determined byits compatibility with the rubber component and by its ability toimprove the tackiness of a material.

"Low molecular weight," as defined herein with reference to resins,means resins having a weight average molecular weight of less than about50,000.

Resins and tackifiers are used in some preferred formulations of thepreferred gel cushioning medium.

d. Oils

The term "oil" is defined herein as naturally occurring hydrocarbonliquids, the carbons of which are primarily saturated with hydrogenatoms. Oils preferred for use in the preferred gel are mineral oils.

"Paraffinic" oils have include straight-chain or branched-chainstructures. "Naphthenic" oils include cyclic hydrocarbon structures.When an oil contains both paraffinic- and naphthenic-type structures,the relative concentrations of each type of structure determine whetherthe oil is identified as naphthenic or paraffinic.

"Oil viscosity" is defined herein as the measurement of time it takes agiven volume of oil to pass through an orifice, such as a capillarytube. Viscosity measurements include the Saybolt universal second (SUS),stokes (s) and centistokes (cs).

e. Molecular Weight

"Number Average Molecular Weight" (M_(n)), as determined by gelpermeation chromatography, provides information about the lowermolecular weight parts of a substance which includes hydrocarbonmolecules.

"Weight Average Molecular Weight" (M_(w)), as determined by gelpermeation chromatography, indicates the average molecular weight ofhydrocarbon molecules in a substance. This is the value that is commonlyused in reference to the molecular weight of a hydrocarbon molecule.

"Z-Average Molecular Weight" (M_(z)), as determined by gel permeationchromatography, is used as an indication of the high-molecular-weightportion of a substance which includes hydrocarbon molecules. When thesubstance is a resin, the Z-average molecular weight indicates thecompatibility and adhesive properties of that resin.

Molecular weight values may also be determined by any of several othermethods, such as the Flory viscosity method, the Staudinger viscositymethod, light scattering in combination with high performance liquidchromatography (HPLC), and others.

f. Cloud Point Tests

The following values, which are determined by cloud point tests, areuseful in determining the compatibility of a resin with different typesof materials.

"MMAP," as defined herein, is a measurement of aromatic solubility anddetermines the aliphatic/aromatic character of a resin. The MMAP valueis obtained by dissolving a resin in a high temperature mixture of onepart methylcyclohexane and two parts aniline, and cooling the solutionwhile mixing to determine the temperature at which the mixture startsbecoming cloudy, which is commonly referred to as the cloud point. Thelower the MMAP value, the greater the aromaticity and lower thealiphaticity of the resin.

"DACP," as defined herein, is a value which determines the polarity of aresin due to the highly polar nature of the solvent system. In order todetermine the DACP value of resin, the resin must first be dissolved ina heated 1:1 mixture of xylene and 4-hydroxy-4-methyl-2-pentanone. Thesolution is then cooled with mixing. The temperature at which thesolution begins becoming opaque is the cloud point, which is the DACPvalue.

Since specific adhesion is related to the polarity of a resin, the DACPvalue can be used as a specific adhesion indicator. Lower DACP valuesindicate greater specific adhesion.

"OMSCP," as defined herein, is a value which is related to the molecularweight and molecular weight distribution of a resin. OMSCP can determinethe compatibility characteristics of a resin/polymer system. The higherthe OMS cloud point, the greater the molecular weight and the molecularweight distribution of a resin. In particular, high OMSCP values canindicate the presence of high molecular weight materials (of Z-averagemolecular weight).

The term "OMSCP" is derived from the method for determining OMSCPvalues. A resin is first dissolved in a high temperature mixture ofodorless mineral spirits (OMS). The solution is then cooled with mixing.The temperature at which the mixture starts becoming cloudy is referredto as the cloud point (CP), or OMSCP value.

3. Material Formulations

a. Elastomer Component

Preferably, the compositions of the preferred gel materials for use inthe present invention are low durometer (as defined below) thermoplasticelastomeric compounds and visco-elastomeric compounds which include aprinciple polymer component, an elastomeric block copolymer componentand a plasticizer component.

The elastomer component of the preferred gel material includes atriblock polymer of the general configuration A-B-A, wherein the Arepresents a crystalline polymer such as a monoalkenylarene polymer,including but not limited to polystyrene and functionalized polystyrene,and the B is an elastomeric polymer such as polyethylene, polybutylene,poly(ethylene/butylene), hydrogenated poly(isoprene), hydrogenatedpoly(butadiene), hydrogenated poly(isoprene+butadiene),poly(ethylene/propylene) or hydrogenatedpoly(ethylene/butylene+ethylene/propylene), or others. The A componentsof the material link to each other to provide strength, while the Bcomponents provide elasticity. Polymers of greater molecular weight areachieved by combining many of the A components in the A portions of eachA-B-A structure and combining many of the B components in the B portionof the A-B-A structure, along with the networking of the A-B-A moleculesinto large polymer networks.

A preferred elastomer for making the preferred gel material is a veryhigh to ultra high molecular weight elastomer and oil compound having anextremely high Brookfield Viscosity (hereinafter referred to as"solution viscosity"). Solution viscosity is generally indicative ofmolecular weight. "Solution viscosity" is defined as the viscosity of asolid when dissolved in toluene at 25-30° C., measured in centipoises(cps). "Very high molecular weight" is defined herein in reference toelastomers having a solution viscosity, 20 weight percent solids in 80weight percent toluene, the weight percentages being based upon thetotal weight of the solution, from greater than about 20,000 cps toabout 50,000 cps. An "ultra high molecular weight elastomer" is definedherein as an elastomer having a solution viscosity, 20 weight percentsolids in 80 weight percent toluene, of greater than about 50,000 cps.Ultra high molecular weight elastomers have a solution viscosity, 10weight percent solids in 90 weight percent toluene, the weightpercentages being based upon the total weight of the solution, of about800 to about 30,000 cps and greater. The solution viscosities, in 80weight percent toluene, of the A-B-A block copolymers useful in theelastomer component of the preferred gel cushioning material aresubstantially greater than 30,000 cps. The solution viscosities, in 90weight percent toluene, of the preferred A-B-A elastomers useful in theelastomer component of the preferred gel are in the range of about 2,000cps to about 20,000 cps. Thus, the preferred elastomer component of thepreferred gel material has a very high to ultra high molecular weight.

Applicant has discovered that, after surpassing a certain optimummolecular weight range, some elastomers exhibit lower tensile strengththan similar materials with optimum molecular weight copolymers. Thus,merely increasing the molecular weight of the elastomer will not alwaysresult in increased tensile strength.

The elastomeric B portion of the preferred A-B-A polymers has anexceptional affinity for most plasticizing agents, including but notlimited to several types of oils, resins, and others. When the networkof A-B-A molecules is denatured, plasticizers which have an affinity forthe B block can readily associate with the B blocks. Upon renaturationof the network of A-B-A molecules, the plasticizer remains highlyassociated with the B portions, reducing or even eliminating plasticizerbleed from the material when compared with similar materials in theprior art, even at very high oil:elastomer ratios. The reason for thisperformance may be any of the plasticization theories explained above(i.e., lubricity theory, gel theory, mechanistic theory, and free volumetheory).

The elastomer used in the preferred gel cushioning medium is preferablyan ultra high molecular weight polystyrene-hydrogenatedpoly(isoprene+butadiene)-polystyrene, such as those sold under the brandnames SEPTON 4045, SEPTON 4055 and SEPTON 4077 by Kuraray, an ultra highmolecular weight polystyrene-hydrogenated polyisoprene-polystyrene suchas the elastomers made by Kuraray and sold as SEPTON 2005 and SEPTON2006, or an ultra high molecular weight polystyrene-hydrogenatedpolybutadiene-polystyrene, such as that sold as SEPTON 8006 by Kuraray.High to very high molecular weight polystyrene-hydrogenatedpoly(isoprene+butadiene)-polystyrene elastomers, such as that sold underthe trade name SEPTON 4033 by Kuraray, are also useful in someformulations of the preferred gel material because they are easier toprocess than the preferred ultra high molecular weight elastomers due totheir effect on the melt viscosity of the material.

Following hydrogenation of the midblocks of each of SEPTON 4033, SEPTON4045, SEPTON 4055, and SEPTON 4077, less than about five percent of thedouble bonds remain. Thus, substantially all of the double bonds areremoved from the midblock by hydrogenation.

Applicant's most preferred elastomer for use in the preferred gel isSEPTON 4055 or another material that has similar chemical and physicalcharacteristics. SEPTON 4055 has the optimum molecular weight(approximately 300,000, as determined by Applicant's gel permeationchromatography testing). SEPTON 4077 has a somewhat higher molecularweight, and SEPTON 4045 has a somewhat lower molecular weight thanSEPTON 4055. Materials which include either SEPTON 4045 or SEPTON 4077as the primary block copolymer typically have lower tensile strengththan similar materials made with SEPTON 4055.

Kuraray Co. Ltd. of Tokyo, Japan has stated that the solution viscosityof SEPTON 4055, the most preferred A-B-A triblock copolymer for use inthe preferred gel material, 10% solids in 90% toluene at 25° C., isabout 5,800 cps. Kuraray also said that the solution viscosity of SEPTON4055, 5% solids in 95% toluene at 25° C., is about 90 cps. AlthoughKuraray has not provided a solution viscosity, 20% solids in 80% tolueneat 25° C., an extrapolation of the two data points given shows that sucha solution viscosity would be about 400,000 cps. Applicant reads theprior art as consistently teaching away from such high solutionviscosities.

Applicant confirmed Kuraray's data by having an independent laboratory,SGS U.S. Testing Company Inc. of Fairfield, N.J., test the solutionviscosity of SEPTON 4055. When SGS attempted to dissolve 20% solids in80% toluene at 25° C., the resulting material did not resemble asolution. Therefore, SGS determined the solution viscosity of SEPTON4055 using 10% solids in 90% toluene at 25° C., which resulted in a3,040 cps solution.

Other materials with chemical and physical characteristics similar tothose of SEPTON 4055 include other A-B-A triblock copolymers which havea hydrogenated midblock polymer that is made up of at least about 30%isoprene monomers and at least about 30% butadiene monomers, thepercentages being based on the total number of monomers that make up themidblock polymer. Similarly, other A-B-A triblock copolymers which havea hydrogenated midblock polymer that is made up of at least about 30%ethylene/propylene monomers and at least about 30% ethylene/butylenemonomers, the percentages being based on the total number of monomersthat make up the midblock polymer, are materials with chemical andphysical characteristics similar to those of SEPTON 4055.

Mixtures of block copolymer elastomers are also useful as the elastomercomponent of some of the formulations of the preferred gel cushioningmedium. In such mixtures, each type of block copolymer contributesdifferent properties to the material. For example, high strengthtriblock copolymer elastomers are desired to improve the tensilestrength and durability of a material. However, some high strengthtriblock copolymers are very difficult to process with someplasticizers. Thus, in such a case, block copolymer elastomers whichimprove the processability of the materials are desirable.

In particular, the process of compounding SEPTON 4055 with plasticizersmay be improved via a lower melt viscosity by using a small amount ofmore flowable elastomer such as SEPTON 8006, SEPTON 2005, SEPTON 2006,or SEPTON 4033, to name only a few, without significantly changing thephysical characteristics of the material.

In a second example of the usefulness of block copolymer elastomermixtures in the preferred gel materials, many block copolymers are notgood compatibilizers. Other block copolymers readily form compatiblemixtures, but have other undesirable properties. Thus, the use of smallamount of elastomers which improve the uniformity with which a materialmixes are desired. KRATON® G 1701, manufactured by Shell ChemicalCompany of Houston, Tex., is one such elastomer that improves theuniformity with which the components of the preferred gel material mix.

Many other elastomers, including but not limited to triblock copolymersand diblock copolymers are also useful in the preferred gel material.Applicant believes that elastomers having a significantly highermolecular weight than the ultra-high molecular weight elastomers usefulin the preferred gel material increase the softness thereof, butdecrease the strength of the gel. Thus, high to ultra high molecularweight elastomers, as defined above, are desired for use in thepreferred gel material due to the strength of such elastomers whencombined with a plasticizer.

b. Additives

i. Polarizable Plasticizer Bleed-Reducing Additives

Preferably, the gel materials used in the cushions of the presentinvention do not exhibit migration of plasticizers, even when placedagainst materials which readily exhibit a high degree of capillaryaction, such as paper, at room temperature.

A preferred plasticizer bleed-reducing additive that is useful in thepreferred gel cushioning material includes hydrocarbon chains withreadily polarizable groups thereon. Such polarizable groups include,without limitation, halogenated hydrocarbon groups, halogens, nitrites,and others. Applicant believes that the polarizability of such groups onthe hydrocarbon molecule of the bleed-reducing additive have a tendencyto form weak van der Waals bonding with the long hydrocarbon chains ofthe rubber portion of an elastomer and with the plasticizer molecules.Due to the great length of typical rubber polymers, several of thebleed-reducers will be attracted thereto, while fewer will be attractedto each plasticizer molecule. The bleed-reducing additives are believedto hold the plasticizer molecules and the elastomer molecules thereto,facilitating attraction between the elastomeric block and theplasticizer molecule. In other words, the preferred bleed-reducingadditives are believed to attract a plasticizer molecule at onepolarizable site, while attracting an elastomeric block at anotherpolarizable site, thus maintaining the association of the palsticizermolecules with the elastomer molecules, which inhibits exudation of theplasticizer molecules from the elastomer-plasticizer compound. Thus,each of the plasticizer molecules is preferably attracted to anelastomeric block by means of a bleed-reducing additive.

The preferred bleed-reducing additives that are useful in the preferredgel material have a plurality of polarizable groups thereon, whichfacilitate bonding an additive molecule to a plurality of elastomermolecules and/or plasticizer molecules. It is believed that an additivemolecule with more polarizable sites thereon will bond to moreplasticizer molecules. Preferably, the additive molecules remain in aliquid or a solid state during processing of the gel material.

The most preferred bleed-reducing additives for use in the preferred gelmaterial are halogenated hydrocarbon additives such as those sold underthe trade name DYNAMAR™ PPA-791, DYNAMAR™ PPA-790, DYNAMAR™ FX-9613, andFLUORAD® FC 10 Fluorochemical Alcohol, each by 3M Company of St. Paul,Minn. Other additives are also useful to reduce plasticizer exudationfrom the preferred gel material. Such additives include, withoutlimitation, other halogenated hydrocarbons sold under the trade nameFLUORAD®, including without limitation FC-129, FC-135, FC-430, FC-722,FC-724, FC-740, FX-8, FX-13, FX-14 and FX-189; halogentated hydrocarbonssuch as those sold under the trade name ZONYL®, including withoutlimitation FSN 100, FSO 100, PFBE, 8857A, ™, BA-L, BA-N, TBC and FTS,each of which are manufactured by du Pont of Wilmington, Del.;halogenated hydrocarbons sold under the trade name EMCOL by Witco Corpof Houston, Tex., including without limitation 4500 and DOSS; otherhalogenated hydrocarbons sold by 3M under the trade name DYNAMAR™;chlorinated polyethylene elastomer (CPE), distributed by Harwick, Inc.of Akron, Ohio; chlorinated paraffin wax, distributed by Harwick, Inc.;and others.

ii. Detackifiers

The preferred material may include a detackifier. Tack is not adesirable feature in many potential uses for the cushions of theinvention. However, some of the elastomeric copolymers and plasticizersuseful in the preferred cushioning media for the cushioning elements ofthe present invention may impart tack to the media.

Soaps, detergents and other surfactants have detackifying abilities andare useful in the preferred gel material. "Surfactants," as definedherein, refers to soluble surface active agents which contain groupsthat have opposite polarity and solubilizing tendencies. Surfactantsform a monolayer at interfaces between hydrophobic and hydrophilicphases; when not located at a phase interface, surfactants formmicelles. Surfactants have detergency, foaming, wetting, emulsifying anddispersing properties. Sharp, D. W. A., DICTIONARY OF CHEMISTRY, 381-82(Penguin, 1990). For example, coco diethanolamide, a common ingredientin shampoos, is useful in the preferred gel material as a detackifyingagent. Coco diethanolamide resists evaporation, is stable, relativelynon-toxic, non-flammable and does not support microbial growth. Manydifferent soap or detergent compositions could be used in the materialas well.

Other known detackifiers include glycerin, epoxidized soybean oil,dimethicone, tributyl phosphate, block copolymer polyether, diethyleneglycol mono oleate, tetraethyleneglycol dimethyl ether, and silicone, toname only a few. Glycerine is available from a wide variety of sources.Witco Corp. of Greenwich, Connecticut sells epoxidized soybean oil asDRAPEX 6.8. Dimethicone is available from a variety of vendors,including GE Specialty Chemicals of Parkersburg, W.Va. under the tradename GE SF 96-350. C. P. Hall Co. of Chicago, Ill. markets blockcopolymer polyether as PLURONIC L-61. C. P. Hall Co. also manufacturesand markets diethylene glycol mono oleate under the name DiglycolOleate--Hallco CPH-I-SE. Other emulsifiers and dispersants are alsouseful in the preferred gel material. Tetraethyleneglycol dimethyl etheris available under the trade name TETRAGLYME from Ferro Corporation ofZachary, La. Applicant believes that TETRAGLYME also reduces plasticizerexudation from the preferred gel material.

iii. Antioxidants

The preferred gel material also includes additives such as anantioxidant. Antioxidants such as those sold under the trade namesIRGANOX® 1010 and IRGAFOS® 168 by Ciba-Geigy Corp. of Tarrytown, N.Y.are useful by themselves or in combination with other antioxidants inthe preferred materials of the present invention.

Antioxidants protect the preferred gel materials against thermaldegradation during processing, which requires or generates heat. Inaddition, antioxidants provide long term protection from free radicals.A preferred antioxidant inhibits thermo-oxidative degradation of thecompound or material to which it is added, providing long termresistance to polymer degradation. Preferably, an antioxidant added tothe preferred gel cushioning medium is useful in food packagingapplications, subject to the provisions of 21 C.F.R. § 178.2010 andother laws.

Heat, light (in the form of high energy radiation), mechanical stress,catalyst residues, and reaction of a material with impurities all causeoxidation of the material. In the process of oxidation, highly reactivemolecules known as free radicals are formed and react in the presence ofoxygen to form peroxy free radicals, which further react with organicmaterial (hydro-carbon molecules) to form hydroperoxides.

The two major classes of antioxidants are the primary antioxidants andthe secondary antioxidants. Peroxy free radicals are more likely toreact with primary antioxidants than with most other hydrocarbons. Inthe absence of a primary antioxidant, a peroxy free radical would breaka hydrocarbon chain. Thus, primary antioxidants deactivate a peroxy freeradical before it has a chance to attack and oxidize an organicmaterial.

Most primary antioxidants are known as sterically hindered phenols. Oneexample of sterically hindered phenol is the C₇₃ H₁₀₈ O₁₂ marketed byCiba-Geigy as IRGANOX® 1010, which has the chemical name3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid,2,2-bis[[3-[3,5-bis(dimethylethyl)4-hydroxyphenyl]-1-oxopropoxy]methyl]1,3-propanediylester. The FDA refers to IRGANOX® 1010 astetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnimate)]methane.Other hindered phenols are also useful as primary antioxidants in thepreferred material.

Similarly, secondary antioxidants react more rapidly with hydroperoxidesthan most other hydrocarbon molecules. Secondary antioxidants have beenreferred to as hydroperoxide decomposers. Thus, secondary antioxidantsprotect organic materials from oxidative degradation by hydroperoxides.

Commonly used secondary antioxidants include the chemical classes ofphosphites/phosphonites and thioesters, many of which are useful in thepreferred gel material. The hydroperoxide decomposer used by Applicantis a C₄₂ H₆₃ O₃ P phosphite known asTris(2,4-di-tert-butylphenyl)phosphite and marketed by Ciba-Geigy asIRGAFOS® 168.

It is known in the art that primary and secondary antioxidants formsynergistic combinations to ward off attacks from both peroxy freeradicals and hydroperoxides.

Other antioxidants, including but not limited to multi-functionalantioxidants, are also useful in the preferred material. Multifunctionalantioxidants have the reactivity of both a primary and a secondaryantioxidant. IRGANOX® 1520 D, manufactured by Ciba-Geigy is one exampleof a multifunctional antioxidant. Vitamin E antioxidants, such as thatsold by Ciba-Geigy as IRGANOX® E17, are also useful in the preferredcushioning material for use in the cushions of the present invention.

Preferably, the preferred gel material includes up to about three weightpercent antioxidant, based on the weight of the elastomer component,when only one type of antioxidant is used. The material may include aslittle as 0.1 weight percent of an antioxidant, or no antioxidant atall. When a combination of antioxidants is used, each may comprise up toabout three weight percent, based on the weight of the elastomercomponent. Additional antioxidants may be added for severe processingconditions involving excessive heat or long duration at a hightemperature.

Applicant believes that the use of excess antioxidants reduces oreliminates tack on the exterior surface of the preferred gel material.Excess antioxidants appear to migrate to the exterior surface of thematerial following compounding of the material. Such apparent migrationoccurs over substantial periods of time, from hours to days or evenlonger.

iv. Flame retardants

Flame retardants may also be added to the preferred gel materials. Flameretardants useful in the cushioning elements of the present inventioninclude but are not limited to diatomaceous earth flame retardants soldas GREAT LAKES DE 83R and GREAT LAKES DE 79 by Great Lakes Filter,Division of Acme Mills Co. of Detroit, Mich. Most flame retardants thatare useful in elastomeric materials are also useful in the preferred gelmaterial. In particular, Applicant prefers the use of food grade flameretardants which do not significantly diminish the physical propertiesof the preferred gel material.

Chemical blowing agents, such as SAFOAM® FP-40, manufactured by ReedyInternational Corporation of Keyport, N.J. and others are useful formaking a gel cushioning medium that is self-extinguishing.

v. Colorants

Colorants may also be used in the preferred gel materials for use in thecushions of the present invention. Any colorant which is compatible withelastomeric materials may be used in the materials. In particular,Applicant prefers to use aluminum lake colorants such as thosemanufactured by Warner Jenkinson Corp. of St. Louis, Mo.; pigmentsmanufactured by Day Glo Color Corp. of Cleveland, Ohio; Lamp Black, suchas that sold by Spectrum Chemical Manufacturing Corp. of Gardena,Calif.; and Titanium Dioxide (white). By using these colorants, the gelmaterial takes on intense shades of colors, including but not limited topink, red, orange, yellow, green, blue, violet, brown, flesh, white andblack.

vi. Paint

The preferred gel cushioning medium may also be painted.

vii. Other additives

Other additives may also be added to the preferred gel material.Additives such as foaming facilitators, tack modifiers, plasticizerbleed modifiers, flame retardants, melt viscosity modifiers, melttemperature modifiers, tensile strength modifiers, and shrinkageinhibitors are useful in specific formulations of the preferred gelmaterial.

Melt temperature modifiers useful in the preferred gel includecross-linking agents, hydrocarbon resins, diblock copolymers of thegeneral configuration A-B and triblock copolymers of the generalconfiguration A-B-A wherein the end block A polymers includefunctionalized styrene monomers, and others.

Tack modifiers which tend to reduce tack and which are useful in thepreferred gel include surfactants, dispersants, emulsifiers, and others.Tack modifiers which tend to increase the tack of the material and whichare useful in the material include hydrocarbon resins, polyisobutylene,butyl rubber and others.

Foam facilitators that are useful in the gel material includepolyisobutylene, butyl rubber, surfactants, emulsifiers, dispersants andothers.

Plasticizer bleed modifiers which tend to reduce plasticizer exudationfrom the preferred material and which are useful therein includehydrocarbon resins, elastomeric diblock copolymers, polyisobutylene,butyl rubber, transpolyoctenylene rubber ("tor rubber"), and others.

Flame retardants useful in the preferred gel include halogenated flameretardants, non-halogenated flame retardants, and volatile, non-oxygengas forming chemicals and compounds.

Melt viscosity modifiers that tend to reduce the melt viscosity of thepre-compounded component mixture of the preferred cushioning mediuminclude hydrocarbon resins, transpolyoctenylene rubber, castor oil,linseed oil, non-ultra high molecular weight thermoplastic rubbers,surfactants, dispersants, emulsifiers, and others.

Melt viscosity modifiers that tend to increase the melt viscosity of thepre-compounded component mixture of the preferred gel material includehydrocarbon resins, butyl rubber, polyisobutylene, additional triblockcopolymers having the general configuration A-B-A and a molecular weightgreater than that of each of the block copolymers in the elastomericblock copolymer component of the material, particulate fillers,microspheres, butadiene rubber, ethylene/propylene rubber,ethylene/butylene rubber, and others.

Tensile strength modifiers which tend to increase the tensile strengthof the preferred gel material for use in the cushions of the presentinvention include mid block B-associating hydrocarbon resins,non-end-block solvating hydrocarbon resins which associate with the endblocks, particulate reinforcers, and others.

Shrinkage inhibitors, which tend to reduce shrinkage of the gel materialfollowing compounding, that are useful in the material includehydrocarbon resins, particulate fillers, microspheres,transpolyoctenylene rubber, and others.

c. Microspheres

Microspheres may also be added to the preferred gel material. The gelmaterial may contain up to about 90% microspheres, by volume. In onepreferred microsphere-containing formulation of the preferred gelmaterial, microspheres make up at least about 30% of the total volume ofthe material. A second preferred microsphere-containing formulation ofthe preferred gel cushioning medium includes at least about 50%microspheres, by volume.

Different types of microspheres contribute various properties to thematerial. For example, hollow acrylic microspheres, such as thosemarketed under the brand name MICROPEARL, and generally in the 20 to 200micron size range, by Matsumoto Yushi-Seiyaku Co., Ltd. of Osaka, Japan,lower the specific gravity of the material. In other formulations of thegel, the microspheres may be unexpanded DU(091-80), which expand duringprocessing of the preferred gel cushioning medium, or pre-expanded DE(091-80) acrylic microspheres from Expancel Inc. of Duluth, Ga.

In formulations of the preferred material which include hollow acrylicmicrospheres, the microspheres preferably have substantiallyinstantaneous rebound when subjected to a compression force whichcompresses the microspheres to a thickness of up to about 50% of theiroriginal diameter or less.

Hollow microspheres also decrease the specific gravity of the gelmaterial by creating gas pockets therein. In many cushioningapplications, very low specific gravities are preferred. The specificgravity of the preferred gel cushioning medium may range from about 0.06to about 1.30, depending in part upon the amount and specific gravity offillers and additives, including microspheres and foaming agents. Inmany cushioning applications of the present invention, a gel materialhaving a specific gravity of less than about 0.50 is preferred. When agel material preferred for use in cushions according to the presentinvention includes the preferred microspheres, the microspheres must bedispersed, on average, at a distance of about one-and-a-half (1.5) timesthe average microsphere diameter or a lesser distance from one anotherin order to achieve a specific gravity of less than about 0.50. Aspecific gravity of less than about 0.30 is preferred for use in somecushions according to this invention. Other formulations of thepreferred gel material have specific gravities of less than about 0.65,less than about 0.45, and less than about 0.25.

MICROPEARL and EXPANCEL acrylic microspheres are preferred because oftheir highly flexible nature, as explained above, which tend to notrestrict deformation of the thermoplastic elastomer. Glass, ceramic, andother types of microspheres may also be used in the thermoplastic gelmaterial, but are less preferred.

d. Plasticizer Component

As explained above, plasticizers allow the midblocks of a network oftriblock copolymer molecules to move past one another. Thus, Applicantbelieves that plasticizers, when trapped within the three dimensionalweb of triblock copolymer molecules, facilitate the disentanglement andelongation of the elastomeric midblocks as a load is placed on thenetwork. Similarly, Applicant believes that plasticizers facilitaterecontraction of the elastomeric midblocks following release of theload. The plasticizer component of the preferred gel cushioning mediummay include oil, resin, a mixture of oils, a mixture of resins, otherlubricating materials, or any combination of the foregoing.

i. Oils

The plasticizer component of the preferred gel material may include acommercially available oil or mixture of oils. The plasticizer componentmay include other plasticizing agents, such as liquid oligomers andothers, as well. Both naturally derived and synthetic oils are useful inthe preferred gel material. Preferably, the oils have a viscosity ofabout 70 SUS to about 500 SUS at about 100° F. Most preferred for use inthe gel material are paraffinic white mineral oils having a viscosity inthe range of about 90 SUS to about 200 SUS at about 100° F.

One embodiment of a plasticizer component of the preferred gel includesparaffinic white mineral oils, such as those having the brand nameDUOPRIME, by Lyondell Lubricants of Houston, Tex., and the oils soldunder the brand name TUFFLO by Witco Corporation of Petrolia, Pa. Forexample, the plasticizer component of the preferred gel may includeparaffinic white mineral oil such as that sold under the trade nameLP-150 by Witco.

Paraffinic white mineral oils having an average viscosity of about 90SUS, such as DUOPRIME 90, are preferred for use in other embodiments ofthe plasticizer component of the preferred gel cushioning medium.Applicant has found that DUOPRIME 90 and oils with similar physicalproperties can be used to impart the greatest strength to the preferredgel material.

Other oils are also useful as plasticizers in compounding the gelmaterial. Examples of representative commercially available oils includeprocessing oils such as paraffinic and naphthenic petroleum oils, highlyrefined aromatic-free or low aromaticity paraffinic and naphthenic foodand technical grade white petroleum mineral oils, and synthetic liquidoligomers of polybutene, polypropene, polyterpene, etc., and others. Thesynthetic series process oils are oligomers which are permanently fluidliquid non-olefins, isoparaffins or parafrins. Many such oils are knownand commercially available. Examples of representative commerciallyavailable oils include Amoco® polybutenes, hydrogenated polybutenes andpolybutenes with epoxide functionality at one end of the polybutenepolymer. Examples of such Amoco polybutenes include: L-14 (320 M_(n)),L-50 (420 M_(n)), L-100 (460 M_(n)), H-15 (560 M_(n)), H-25 (610 M_(n)),H-35 (660 M_(n)), H-50 (750 M_(n)), H-100 (920 M_(n)), H-300 (1290M_(n)), L-14E (27-37 cst @ 100° F. Viscosity), L-300E (635-690 cst @210° F. Viscosity), Actipol E6 (365 M_(n)), E16 (973 M_(n)), E23 (1433M_(n)) and the like. Examples of various commercially available oilsinclude: Bayol, Bernol, American, Blandol, Drakeol, Ervol, Gloria,Kaydol, Litetek, Marcol, Parol, Peneteck, Primol, Protol, Sontex, andthe like.

ii. Resins

Resins useful in the plasticizer component of the preferred gel materialinclude, but are not limited to, hydrocarbon-derived and rosin-derivedresins having a ring and ball softening point of up to about 150° C.,more preferably from about 0° C. to about 25° C., and a weight averagemolecular weight of at least about 300.

For use in many of the cushions according to the invention, Applicantprefers the use of resins or resin mixtures which are highly viscousflowable liquids at room temperature (about 23° C.). Plasticizers whichare fluid at room temperature impart softness to the gel material.Although room temperature flowable resins are preferred, resins whichare not flowable liquids at room temperature are also useful in thematerial.

The resins most preferred for use in the preferred gel material have aring and ball softening point of about 18° C.; melt viscosities of about10 poises (ps) at about 61° C., about 100 ps at about 42° C. and about1,000 ps at about 32° C.; an onset T_(g) of about -20° C.; a M value of68° C.; a DACP value of 15° C.; an OMSCP value of less than 40° C.; aM_(n) of about 385; a M_(w) of about 421; and a M_(z) of about 463. Onesuch resin is marketed as REGALREZ® 1018 by Hercules Incorporated ofWilmington, Del. Variations of REGALREZ® 1018 which are useful in thepreferred cushioning material have viscosities including, but notlimited to, 1025 stokes, 1018 stokes, 745 stokes, 114 stokes, andothers.

Room temperature flowable resins that are derived from poly-β-pinene andhave softenening points similar to that of REGALREZ® 1018 are alsouseful in the plasticizer component of the preferred cushioning medium.One such resin, sold as PICCOLYTE® S25 by Hercules Incorporated, has asoftening point of about 25° C.; melt viscosities of about 10 ps atabout 80° C., about 100 ps at about 56° C. and about 1,000 ps at about41° C.; a MMAP value of about 88° C.; a DACP value of about 45° C.; anOMSCP value of less than about -50° C.; a M_(z) of about 4,800; a M_(w)of about 1,950; and a M_(n) of about 650. Other PICCOLYTE® resins mayalso be used in the preferred gel material.

Another room temperature flowable resin which is useful in theplasticizer component of the preferred material is marketed as ADTAC® LVby Hercules Incorporated. That resin has a ring and ball softening pointof about 5° C.; melt viscosities of about 10 ps at about 62° C., about100 ps at about 36° C. and about 1,000 ps at about 20° C.; a MMAP valueof about 93° C.; a DACP value of about 44° C.; an OMSCP value of lessthan about -40° C.; a M_(z) of about 2,600; a M_(w) of about 1,380; anda M_(n) of about 800.

Resins such as the liquid aliphatic C-5 petroleum hydrocarbon resin soldas WINGTACK® 10 by the Goodyear Tire & Rubber Company of Akron, Ohio andother WINGTACK® resins are also useful in the gel material. WINGTACK® 10has a ring and ball softening point of about 10° C.; a BrookfieldViscosity of about 30,000 cps at about 25° C.; melt viscosities of about10 ps at about 53° C. and about 100 ps at about 34° C.; an onset T_(g)of about -37.7° C.; a M_(n) of about 660; a M_(w) of about 800; a 1:1polyethylene-to-resin ratio cloud point of about 89° C.; a 1:1microcrystalline wax-to-resin ratio cloud point of about 77° C.; and a1:1 paraffin wax-to-resin ratio cloud point of about 64° C.

Resins that are not readily flowable at room temperature (i.e., aresolid, semi-solid, or have an extremely high viscosity) or that aresolid at room temperature are also useful in the preferred gel material.One such solid resin is an aliphatic C-5 petroleum hydrocarbon resinhaving a ring and ball softening point of about 98° C.; melt viscositiesof about 100 ps at about 156° C. and about 1000 ps at about 109° C.; anonset T_(g) of about 46.1° C.; a M_(n) of about 1,130; a M_(w) of about1,800; a 1:1 polyethylene-to-resin ratio cloud point of about 90° C.; a1:1 microcrystalline wax-to-resin ratio cloud point of about 77° C.; anda 1:1 paraffin wax-to-resin ratio cloud point of about 64° C. Such aresin is available as WINGTACK® 95 and is manufactured by GoodyearChemical Co.

Polyisobutylene polymers are an example of resins which are not readilyflowable at room temperature and that are useful in the preferred gelmaterial. One such resin, sold as VISTANEX® LM-MS by Exxon ChemicalCompany of Houston, Texas, has a T_(g) of -60° C., a BrookfieldViscosity of about 250 cps to about 350 cps at about 350° F., a Florymolecular weight in the range of about 42,600 to about 46,100, and aStaudinger molecular weight in the range of about 10,400 to about10,900. The Flory and Staudinger methods for determining molecularweight are based on the intrinsic viscosity of a material dissolved indiisobutylene at 20° C.

Glycerol esters of polymerized rosin are also useful as plasticizers inthe preferred gel material. One such ester, manufactured and sold byHercules Incorporated as HERCULES® Ester Gum 10D Synthetic Resin, has asoftening point of about 116° C.

Many other resins are also suitable for use in the gel material. Ingeneral, plasticizing resins are preferred which are compatible with theB block of the elastomer used in the material, and non-compatible withthe A blocks.

In some embodiments of the cushion according to the present invention,tacky materials may be desirable. In such embodiments, the plasticizercomponent of the gel material may include about 20 weight percent ormore, about 40 weight percent or more, about 60 weight percent or more,or up to about 100 weight percent, based upon the weight of theplasticizer component, of a tackifier or tackifier mixture.

iii. Plasticizer Mixtures

The use of plasticizer mixtures in the plasticizer component of thepreferred gel material is useful for tailoring the physicalcharacteristics of the preferred gel material. For example,characteristics such as durometer, tack, tensile strength, elongation,melt flow and others may be modified by combining various plasticizers.

For example, a plasticizer mixture which includes at least about 37.5weight percent of a paraffinic white mineral oil having physicalcharacteristics similar to those of LP-150 (a viscosity of about 150 SUSat about 100° F., a viscosity of about 30 centistokes (cSt) at about 40°C., and maximum pour point of about -35° F.) and up to about 62.5 weightpercent of a resin having physical characteristics similar to those ofREGALREZ® 1018 (such as a softening point of about 20° C.; an onsetT_(g) of about -20° C.; a MMAP value of about 70° C.; a DACP value ofabout 15° C.; an OMSCP value of less than about 40° C.; and M_(w) ofabout 400), all weight percentages being based upon the total weight ofthe plasticizer mixture, could be used in a gel cushioning medium. Whencompared to a material plasticized with the same amount of an oil suchas LP-150, the material which includes the plasticizer mixture hasdecreased oil bleed and increased tack.

Applicant believes that, when resin is included with oil in aplasticizer mixture of the preferred gel for use in cushions accordingto the present invention, the material exhibits reduced oil bleed. Forexample, a formulation of the material which includes a plasticizingcomponent which has about three parts plasticizing oil (such as LP-150),and about five parts plasticizing resin (such as REGALREZ® 1018)exhibits infinitesimal oil bleed at room temperature, if any, even whenplaced against materials with high capillary action, such as paper.Prior art thermoplastic elastomers bleed noticeably under thesecircumstances.

The plasticizer:block copolymer elastomer ratio, by total combinedweight of the plasticizer component and the block copolymer elastomercomponent, of the preferred gel cushioning material for use in thecushions of the present invention ranges from as low as about 1:1 orless to higher than about 25:1. In applications where plasticizer bleedis acceptable, the ratio may as high as about 100:1 or more. Especiallypreferred are plasticizer:block copolymer ratios in the range of about2.5:1 to about 8:1. A preferred ratio, such as 5:1 provides the desiredamounts of rigidity, elasticity and strength for many typicalapplications. Another preferred plasticizer to block copolymer elastomerratio of the preferred gel material is 2.5:1, which has an unexpectedlyhigh amount of strength and elongation.

4. Compounding Methods

As used herein, the term "liquification" refers to the placement of theblock copolymer elastomer and plasticizer components of the preferredgel cushioning medium in a liquid state, such as a molten state or adissolved state.

a. Melt Blending

A preferred method for manufacturing the preferred gel material includesmixing the plasticizer, block copolymer elastomer and any additivesand/or fillers (e.g., microspheres), heating the mixture to meltingwhile agitating the mixture, and cooling the compound. This process isreferred to as "melt blending."

Excessive heat is known to cause the degradation of the elastomeric Bportion of A-B-A and A-B block copolymers which are the preferredelastomer component of the preferred gel material for use in thecushions of the present invention. Similarly, maintaining blockcopolymers at increased temperatures over prolonged periods of timeoften results in the degradation of the elastomeric B portion of A-B-Aand A-B block copolymers. As the B molecules of an A-B-A triblockcopolymer break, the triblock is separated into two diblock copolymershaving the general configuration A-B. While it is believed by some inthe art that the presence of A-B diblock copolymers in oil-containingplasticizer-extended A-B-A triblock copolymers reduces plasticizerbleed-out, high amounts of A-B copolymers significantly reduce thestrength of the preferred gel material. Thus, Applicant believes that itis important to minimize the compounding temperatures and the amount oftime to which the material is exposed to heat.

The plasticizers, any additives and/or fillers, and the A-B-A copolymersare premixed. Preferably, if possible, hydrophobic additives aredissolved into the plasticizer prior to adding the plasticizer componentto the elastomer component. If possible, hydrophilic additives andparticulate additives are preferably emulsified or mixed into theplasticizer of a preferred gel material prior to adding the elastomercomponents. The mixture is then quickly heated to melting. Preferably,the temperature of the mixture does not exceed the volatilizationtemperature of any component. For some of the preferred gel materials,Applicant prefers temperatures in the range of about 270° F. to about290° F. For other gel materials, Applicant prefers temperatures in therange of about 360° F. to about 400° F. A melting time of about tenminutes or less is preferred. A melting time of about five minutes orless is more preferred. Even more preferred are melting times of aboutninety seconds or less. Stirring, agitation, or, most preferably, highshearing forces are preferred to create a homogeneous mixture. Themixture is then cast, extruded, injection molded, etc.

Next, the mixture is cooled. When injection molding equipment and castmolds are used, the mixture may be cooled by running coolant through themold, by the thermal mass of the mold itself, by room temperature, by acombination of the above methods, or other methods. Extruded mixturesare cooled by air or by passing the extruded mixture through coolant.Cooling times of about five minutes or less are preferred. A coolingtime of less than one minute is most preferred.

Use of high shear facilitates short heating times. "High shear", forpurposes of this disclosure, is defined in terms of the length overdiameter (L/D) ratio of a properly designed injection molding singlescrew or extruder single screw. L/D ratios of about 20:1 and highercreate high shear. Twin screws, Banbury mixers and the like also createhigh shear. High shearing with heat mixes compounds at lowertemperatures and faster rates than the use of heat alone or heat withrelatively low-shear mixing. Thus, high shear forces expeditecompounding of the mixture over a relatively short period of time bymore readily forcing the molecules into close association with the Bcomponent of the A-B-A copolymer. Use of high shear also facilitates thedecrease of equipment temperatures. Melt blending techniques whichemploy little or no shear require an external heat source. Thus, inorder to avoid heat loss, the periphery of many types of melt blendingequipment must be heated to a temperature higher than the melttemperature in order to transfer heat and melt a component mixture. Incomparison, high shearing equipment can generate high materialtemperatures directly from the shear forces, substantially reducing oreliminating the need for external heating.

The inventor prefers the use of equipment that produces high shear, suchas twin screw compounding extrusion machinery, to melt blend thepreferred gel cushioning medium. Twin screw extruders such as the ZE25TIEBAR AIR COOLED TWIN SCREW EXTRUDER, with a 35:1 L/D ratio,manufactured by Berstorff Corporation of Charlotte, N.C., are useful forcompounding the preferred gel material. Twin screw compounding extrusionmachinery is desired for compounding the preferred gel material since itgenerates a very high level of shear and because compounding andmolding, casting, extrusion, or foaming are performed in one continuousprocess. Alternatively, the preferred thermoplastic elastomeric may becompounded first, then later formed into a finished product by injectionmolding, extrusion, or some other method.

It was mentioned above that microspheres may be added to the gelmaterial to reduce its specific gravity and to increase its stiffness ordurometer. Applicant has unexpectedly discovered that acrylicmicrospheres remain intact when subjected to the heat and shear ofinjection molding machines and extruders if the time at high temperatureis kept to about five minutes or less.

Other equipment, such as batch mixers are also useful for melt blendingthe preferred gel materials for use in the cushions according to thepresent invention.

b. Solvent Blending

A second preferred method for making the preferred elastomeric compoundscomprises dissolving the elastomeric component in a solvent, adding theplasticizer component and any additives and/or fillers, and removing thesolvent from the mixture.

Aromatic hydrocarbon solvents such as toluene may be used for mixing thepreferred gel compounds. Sufficient solvent is added to the elastomercomponent to dissolve the network of block copolymer molecules.Preferably, the amount of solvent is limited to an amount sufficient fordissolving the network of block copolymer molecules. The elastomers thendissolve in the solvent. Mixing is preferred since it speeds up thesolvation process. Similarly, slightly elevating the mixture temperatureis preferred since it speeds up the solvation process. Next,plasticizer, any additives and any fillers are mixed into the solvatedelastomer. If possible, hydrophobic additives are preferably dissolvedin the plasticizer prior to adding the plasticizer to the principlepolymer, the block copolymer elastomer and the solvent. Preferably, ifpossible, hydrophilic additives and particulate additives are emulsifiedor mixed into the plasticizer prior to adding the elastomer componentsand solvent. The mixture is then cast into a desired shape (accountingfor later shrinkage due to solvent loss) and the solvent is evaporatedfrom the mixture.

Other methods of compounding the preferred materials, including but notlimited to other processes for compounding, modifying and extendingelastomeric materials, are also useful for compounding the preferred gelcushioning medium.

c. Foaming

The preferred gel material may be foamed. "Foaming", as defined herein,refers to processes which form gas bubbles or gas pockets in thematerial. A preferred foamed gel material that is useful in the cushionsof this invention includes gas bubbles dispersed throughout thematerial. Both open cell and closed cell foaming are useful in thepreferred gel material. Foaming decreases the specific gravity of thepreferred material. In many cushioning applications, very low specificgravities are preferred. The specific gravity of the gel material mayrange, after foaming, from about 0.06 to about 1.30.

A preferred foamed formulation of the gel material includes at leastabout 10% gas bubbles or gas pockets, by volume of the material. Morepreferably, when the material is foamed, gas bubbles or gas pockets makeup at least about 20% of the volume of the material. Other foamedformulations of the preferred gel material contain at least about 40%gas bubbles or gas pockets, by volume, and at least about 70% gasbubbles or pockets, by volume.

Various methods for foaming the preferred gel material include, but arenot limited to, whipping or injecting air bubbles into the materialwhile it is in a molten state, adding compressed gas or air to thematerial while it is in the molten state and under pressure, addingwater to the material while it is in the molten state, use of sodiumbicarbonate, and use of chemical blowing agents such as those marketedunder the brand name SAFOAM(® by Reedy International Corporation ofKeyport, N.J. and those manufactured by Boehringer Ingelheim ofIngelheim, Germany under the trade name HYDROCEROL®.

When blowing agents such as sodium bicarbonate and chemical blowingagents are used in the preferred gel material, the material temperatureis preferably adjusted just prior to addition of the blowing agent sothat the material temperature is just above the blowing temperature ofthe blowing agent. Following addition of the blowing agent to thematerial, the material is allowed to cool so that it will retain the gasbubbles or gas pockets formed by the release of gas from the blowingagent. Preferably, the material is quickly cooled to a temperature belowits T_(g). The material will retain more gas bubbles and the gas bubbleswill be more consistently dispersed throughout the material the quickerthe material temperature cools to a temperature below the T_(g).

When a preferred gel material is injection molded in accordance with onepreferred compounding method of the gel material, foaming is preferredjust after the material has been injected into a mold. Thus, as thematerial passes through the injection molding machine nozzle, itstemperature is preferably just higher than the blowing temperature ofthe blowing agent. Preferably, the material is then cooled to atemperature below its T_(g).

Addition of polyisobutylene resin improves the ability of the preferredgel material to foam and retain cells during the foaming process. Onesuch resin, known as VISTANEX® LM-MS, is manufactured by Exxon ChemicalCompany. Similarly, surfactants, dispersants and emulsifiers such asLaureth-23, available from Lonza of Fair Lawn, N.J. under the trade nameETHOSPERSE LA-23, and others may be used to facilitate foaming of thegel material. In formulations which include oil, certain foaming oilssuch as Hydraulic and Transmission Oil, such as that made by SpectrumCorp. of Selmer, Tenn., may also be used in the material to facilitatefoaming of the materials.

Additives which modify the gas permeability of the preferred gelmaterial are preferred when the material is foamed. One such material,manufactured by Rohm & Haas Company of Philadelphia, Pa. and marketedunder the trade name PARALOID® K 400, modifies the gas permeability ofthe preferred gel material, facilitating the material's ability to holdgas bubbles.

When foaming is desired, additives which increase the melt viscosity ormelt body of the material are also useful. One such additive, PARALOID®K 400, is believed to increase the melt viscosity of the material,making it more difficult for gas bubbles to escape from the material asit cools. Another additive, ACRYLOID® F-10, manufactured by Rohm & Haas,is also believed to improve the ability of the material to entrapbubbles.

Another additive, ethylene vinyl acetate (EVA) crosslinks with itselfand/or other molecules to increase the internal structure of thematerial, while reducing the material's melt viscosity. Thus, EVA isalso believed to improve the gas bubble retention of the material. EVAis available from a variety of sources. High viscosity plasticizers,including without limitation DUOPRIME 500, are also believed tofacilitate gas bubble retention.

Additives which act as nucleating agents are also useful for foaming thepreferred gel material. Such additives are helpful in initiating theformation of gas bubbles. Applicant believes that antioxidants,including but not limited to IRGANOX® 1010 and IRGAFOS® 168, act asnucleating agents during foaming of the material. Blowing agents such asthose sold under the trade name SAFOAM® by Reedy International are alsobelieved to have a secondary function as nucleating agents. Examples ofother nucleating agents include talc, carbon black, aluminum stearate,hydrated alumina, titanium dioxide, aluminum lake colorants, and others.

Referring now to FIGS. 40a and 40b, a preferred embodiment of a methodfor foaming the preferred gel cushioning material is shown. FIG. 40aillustrates the preferred embodiment of the foaming method using anextruder 4001. FIG. 10b shows the preferred embodiment of the foamingmethod in an injection molding machine 4001'. Preferably, the gelcushioning medium includes a blowing agent such as SAFOAM® FP-40, whichis added to the non-liquid components of the cushioning medium prior toprocessing. About half of the plasticizer component is then added to thenon-liquid components, which are then fed into extruder 4001 orinjection molding machine 4001'. The remaining plasticizer is added tothe mixture at 4003, 4003' as the mixture moves along the barrel 4004,4004', which houses the screw or screws. Pressurized carbon dioxide(CO₂), which is contained in a CO₂ source 4008, 4008' such as apressurized cannister, is then injected into the barrel. The CO₂ isinjected into the mixture near the end of the barrel 4004, 4004', aftera seal 4006, 4006' and just before the nozzle 4007, 4007'. Preferably, apumping mechanism 4009, 4009' such as a stepping pump, which are widelyused in the industry, is used to increase the pressure in barrel 4004,4004'. The material is then discharged through nozzle 4007, 4007'.

Referring to FIG. 40a, when an extruder 4001 is used to compound andfoam the preferred gel cushioning medium, a gear pump 4010, which ispreferably positioned at the end of nozzle 4007, controls the amount ofpressure in barrel 4004 and inhibits a drop in pressure at the nozzle.As the material is discharged from pump 4010 at 4011, the CO₂ expands,which introduces gas bubbles into the material and foams the material.

With reference to FIG. 40b, when an injection molding machine 4001' isused to compound and foam the preferred gel material, an accumulatorpositioned just before nozzle 4007' increases the material pressure.Following discharge from nozzle 4007', the material passes through aheat exchanger 4012 and into the cavity (not shown) of a mold 4013.Preferably, the CO₂ begins to expand and form gas bubbles in thematerial as the material fills the mold cavity.

Preferably, the CO₂ and the material are maintained at a pressure of atleast about 700 psi just prior to entering the gear pump at theextrusion end of the barrel. More preferably, the material and CO₂ reacha pressure of at least about 900 psi. Most preferably, the CO₂ andmaterial are subjected to a pressure of at least about 1,700 psi. Atpressures of about 1,700 psi and greater, CO₂ acts as a supercriticalfluid.

At such high pressure, the liquid CO₂ solvates the block copolymer andprinciple polymer, which decreases the T_(g) of the mixture. Thus, aspressure is released upon extrusion of the mixture from the nozzle, theCO₂ immediately becomes a gas and the mixture immediately crosses itsT_(g). In other words, as gas bubbles are forming in the material, thematerial begins to solidify. Thus, the number of gas bubbles retained inthe material is increased. CO₂ bubbles are believed to form around theSAFOAM®, which is believed to act as a nucleating agent.

The expansion rate of the CO₂ bubbles and the solidification rate of themixture are varied, depending upon the particular formulation of thematerial. Various other factors also affect how a material will foam,including the rate at which material is fed into the barrel (the "feedrate"), the length of time the material is in the barrel (the "residencetime"), the speed at which the screw or screws rotate (the "screw rpm"),the relative direction each screw rotates and others.

In addition, properties of the material affect the foaming process. Theamount of plasticizer affects a material's ability to foam. For example,when the plasticizer is an oil, materials which include increasedamounts of plasticizer do not foam as readily as similar materials withless plasticizing oil. Applicant believes that as the amount ofplasticizing oil in a material increases, gas bubbles tend to morereadily escape from the material.

d. Lattice Structures

Lattice structures may be made using the preferred gel material, whichis incorporated into the cushion configurations according to the presentinvention. Such lattice structures include multiple overlaid streams ofthe gel material in a lattice-like arrangement. Preferably, the streamsof material have a thickness of less than about one-tenth of an inch.

Formation of the gel material into lattice structures decreases thespecific gravity of the material due to the free space created withinthe lattice structure. Preferably, lattice structures reduce thespecific gravity of the material by at least about 50%.

One method of forming lattice structures includes heating the materialto a molten state and spraying streams of the material to form a desiredlattice structure. Preferably, a hot melt adhesive spray gun, such asthe FP-200 Gun System manufactured by Nordson Corporation of Amherst,Ohio, is used to spray streams of the preferred gel cushioning materialto form a lattice structure.

e. Premixing of Microspheres

In formulations of the preferred material for use in the cushioningelements of this invention which include microspheres, premixing themicrospheres with the plasticizer prior to adding the plasticizer to theelastomeric block copolymer and the polyolefin may result in a moreuniform mixture (i.e., a better final product) and makes themicrosphere-containing gel material easier to process. For example, thematerials may be premixed by hand.

5. Representative Elastomeric Gel Physical Properties and Formulations

When the preferred A-B-A triblock copolymer, plasticizer and additivesare mixed, the resultant material is very strong, yet very elastic andeasily stretched, having a Young's elasticity modulus of only up toabout 1×10⁶ dyne/cm². The preferred elastomeric gel material for use inthe cushioning elements of this invention also has low tack and littleor no oil bleed, both of which are believed to be related to themolecular weight of the uniquely preferred elastomers as well as themolecular structure of the molecular structure of the elastomer and itsinteraction with the plasticizing component. Finally, the preferredelastomeric gel cushioning medium is capable of elongation up to about2400% and more.

EXAMPLES

Examples 1 through 14 include various mixtures of SEPTON 4055 (availablefrom Kuraray) ultra high molecular weight polystyrene-hydrogenatedpoly(isoprene+butadiene)-polystyrene triblock copolymer extended in aplasticizing oil. In addition, the materials of Examples 1 through 14include very minor amounts of IRGANOX® 1010 (about 0.03%), IRGAFOS® 168(about 0.03%), and colorant (about 0.04%).

The material of each of Examples 1 through 14 was compounded in an ISF120VL injection molding machine, manufactured by Toshiba Machine Co. ofTokyo, Japan, with a 20:1 (L/D) high mixing single screw manufactured byAtlantic Feed Screw, Inc. of Cayce, S.C. The temperature in theinjection molding machine was increased stepwise from the point ofinsertion to the injection nozzle. At the point of insertion, thetemperature was about 270° F. Temperatures along the screw were about275° F. and about 280° F., with the temperature increasing as thematerial approached the injection nozzle. The temperature at theinjection nozzle was about 290° F. This gradual increase in temperaturebuilds up pressure during feeding of the material through the injectionmolding machine, providing a more homogeneous mixture of the componentsof the material.

Each of the formulations of Examples 1 through 11 were then injectedinto an aluminum plaque mold and allowed to cure at room temperature forabout 24 hours to about 48 hours. Thereafter, various tests wereperformed on the materials, including percent elongation, tensilestrength at break, and percent oil bleed.

Percent elongation and tensile strength testing were performed inaccordance with American Society for Testing and Materials (ASTM)Standard Test Method D412, using a Model QC-II-30XS-B Electronic TensileTester manufactured by Thwing Albert Instrument Co. of Philadelphia, Pa.Each of samples were O-shaped rings with an outer diameter of about0.500 inch, an inner diameter of about 0.375 inch, a gauge diameter ofabout 0.438 inch, and a mean circumference of about 1.374 inches. Fivesamples of each material were tested for elongation and tensilestrength.

Percent oil bleed was measured by obtaining the combined weight of threedisk-shaped samples of the material, each sample having diameter ofabout 3 cm and a thickness of about 6.5 mm. Two pieces of 12.5 cmdiameter qualitative filter paper having a medium filter speed and anash content of about 0.15%, such as that sold under the trade nameDOUBLE RINGS 102, and manufactured by Xinhua Paper Mill, were thenweighed individually.

The three sample disks were then placed on one of the pieces of filterpaper (which has high capillary action), and the other piece of filterpaper was placed on top of the samples. The material and paper were thenplaced in a plastic bag and pressure-sandwiched between two flat steelplates, each weighing within about 0.5% of about 2285 g. Next, thematerial samples, paper and steel plates were placed in a freezer atabout -4° C. for about 4 hours.

Oil bleed testing was conducted at a low temperature because rubbermolecules are known to constrict at low temperatures. Thus, in theory,when a plasticized material is subjected to cooler temperatures, theattraction of plasticizer to Vander Waals binding sites on the rubbermolecules decreases. Therefore, it has been theorized thatplasticizer-extended materials tend to bleed more at lower temperatures.However, oil tends to flow more slowly at low temperatures, suggestingthat this theory may not be accurate. Nevertheless, this theory has beenwidely accepted. The extreme condition of the pressure and the freezerwas needed for quantitative evaluation since the preferred elastomericgel materials have the advantage over prior art gel materials of notbleeding at all at room temperature without pressure, even when placednext to high capillary action paper. Although John Y. Chen did notreport oil bleed in his patents or patent applications, Applicant'sexperience is that Chen's materials have a higher level of oil bleedthan the preferred elastomeric gel cushioning medium.

Upon removal from the freezer, each piece of the filter paper and thesamples were immediately weighed again. Percent oil bleed was thencalculated by determining the combined weight increase of the filterpapers, dividing that value by the original sample weight andmultiplying the result by 100.

EXAMPLE 1

The material of Example 1 includes eight parts LP 150 mineral oil to onepart SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2375    2400                                                 PSI at Failure    185     190                                                 ______________________________________                                    

In comparison, the material of Chen's patents that has an oil toelastomer ratio of 4:1, which should have higher strength thanApplicant's 8:1 material of Example 1, instead exhibits much lowerelongation and PSI at failure (i.e., tensile strength) values. Thematerial of Example 1 elongates up to about 2,400%, which is 700%greater elongation than Chen's 4:1, which is capable of only 1700%elongation (See, e.g., '213 Patent, Table I, col. 6, lines 18-38).Likewise, the tensile strength at break of Chen's 4:1 gel is only about4×10⁶ dyne/cm², or 58 psi. Thus, the 8:1 material of Example 1 is atleast three times as strong as Chen's 4:1. This is an unexpectedly goodresult since the conventional wisdom concerning gels is that more oilresults in less strength. Applicant doubled the amount of oil used (8:1compared to 4:1) but achieved more than three times the tensile strengthof Chen's material.

EXAMPLE 2

The material of Example 2 includes five parts LP 150 mineral oil to onepart SEPTON 4055.

    ______________________________________                                        5:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             1975    2030                                                 PSI at Failure    335     352                                                 ______________________________________                                    

A comparison of the 5:1 material of Example 2 to the 4:1 material ofChen's patents shows that Chen's material exhibits much lower elongationand PSI at failure (i.e., tensile strength) values. The material ofExample 2 elongates up to about 2,000%, which is about 300% more thanChen's 4:1, which is capable of only 1700% elongation (See, e.g., '213Patent, Table I, col. 6, lines 18-38). Likewise, the tensile strength atbreak of Chen's 4:1 gel is only about 4×10⁶ dyne/cm², which translatesto only about 58 psi. Thus, the 5:1 material of Example 2, despite thepresence of about 25% more oil than Chen's 4:1 material, is aboutfive-and-a-half times as strong as Chen's 4:1.

EXAMPLE 3

The material of Example 3 includes three parts LP 150 mineral oil to onepart SEPTON 4055.

    ______________________________________                                        3:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             1555    1620                                                 PSI at Failure    404     492                                                 ______________________________________                                    

A consideration of both Example 2, a material having a 5:1 oil toelastomer ratio, and Example 3, a material having a 3:1 oil to elastomerratio, indicates that a material with a 4:1 oil to elastomer ratio wouldcompare very favorably to the gel disclosed in U.S. Pat. No. 5,508,334,which issued in the name of John Y. Chen. According to Table I in the'334 patent, Chen's 4:1 KRATON® G-1651-containing material had abreaking strength (i.e., tensile strength) value of 4×10⁶ dyne/cm²,which translates to only about 58 psi.

The elongation at break value was mysteriously omitted from Table I ofthe '334 patent and other Chen patents. However, reference to Table I ofChen's first two issued patents (the '284 and '213 patents) sets thepercent elongation of Chen's 4:1 material at about 1700. Applicantsuspects that Chen omitted this data in later patent applicationsbecause it was either inaccurate or Chen's improved materials failed toexhibit improved properties over his earlier materials.

In comparison, the percent elongation of a 4:1 preferred elastomeric gelmaterial for use in the cushions of the present invention would be atleast about 1800, exceeding the elongation of Chen's 4:1 material byabout 100% or more. Similarly, the tensile strength of a 4:1 materialpreferred for use in the cushions of this invention would be at leastabout 350 psi, and probably in the 370 to 375 psi range. Thus, apreferred elastomeric gel cushioning medium for use in the cushions ofthe present invention with an oil to elastomer ratio of about 4:1 wouldbe about six times a strong as Chen's most preferred 4:1 gel.

The following Examples 4 through 11 have been included to demonstratethe usefulness of various plasticizing oils in the preferred elastomericgel material.

EXAMPLE 4

The material of Example 4 included eight parts of a plasticizer mixtureto one part SEPTON 4055. The eight parts plasticizer mixture includedabout 5.3 parts REGALREZ ® 1018 and about 2.8 parts DUOPRIME ® 90mineral oil.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2480    2520                                                 PSI at Failure    187     195                                                 ______________________________________                                    

EXAMPLE 5

The material of Example 5 included eight parts of EDELEX ® 27 oil to onepart SEPTON 4055. EDELEX ® 27 has an aromatic content of about 1%, whichwould be expected to slightly decrease the tensile strength of thematerial.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2105    2150                                                 PSI at Failure   144      154                                                 Percent Oil bleed                                                                              0.34                                                         ______________________________________                                    

EXAMPLE 6

The material of Example 6 included eight parts of DUOPRIME ® 55 mineraloil to one part SEPTON 4055 .

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             1940    2055                                                 PSI at Failure   280      298                                                 Percent oil bleed                                                                              0.29                                                         ______________________________________                                    

EXAMPLE 7

The material of Example 7 included eight parts of DUOPRIME ® 70 mineraloil to one part SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2000    2030                                                 PSI at Faliure   250      275                                                 Percent oil bleed                                                                              0.41                                                         ______________________________________                                    

EXAMPLE 8

The material of Example 8 included eight parts of DUOPRIME ® 90 mineraloil to one part SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2090    2125                                                 PSI at Failure   306      311                                                 Percent oil bleed                                                                              0.35                                                         ______________________________________                                    

EXAMPLE 9

The material of Example 9 included eight parts of DUOPRIME ® 200 mineraloil to one part SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             1970    2040                                                 PSI at Failure   200      228                                                 Percent oil bleed                                                                              0.20                                                         ______________________________________                                    

EXAMPLE 10

The material of Example 10 included eight parts of DUOPRIME ® 350mineral oil to one part SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             2065    2080                                                 PSI at Failure   267      270                                                 Percent oil bleed                                                                              0.21                                                         ______________________________________                                    

EXAMPLE 11

The material of Example 11 included eight parts of DUOPRIME ® 500mineral oil to one part SEPTON 4055.

    ______________________________________                                        8:1              Average High Value                                           ______________________________________                                        Percent Elongation                                                                             1995    2075                                                 PSI at Failure   194      223                                                 Percent oil bleed                                                                              0.17                                                         ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component  Generic Class   Amount (grams)                                     ______________________________________                                        Septon 4055                                                                              A-B-A copolymer 227.0                                              Duoprime 500 oil                                                                         Plasticizing oil                                                                              2,722.0                                            Irganox 1010                                                                             Antioxidant     4.5                                                Irgafos 168                                                                              Antioxidant     4.5                                                Safoam FP-40                                                                             Foaming agent   14.0                                               Lamp Black Colorant and Foam Bubble                                                                      1.5                                                           Nucleating Agent                                                   ______________________________________                                    

Applicant began foaming the preferred elastomeric gel material to reduceits specific gravity by heating it until the SAFOAM began to degenerateand create CO₂ gas. DUOPRIME 500 oil was selected for use in the examplebecause of its high viscosity (i.e., it would help hold a bubble longerthan a lower viscosity oil). The components were compounded in aninjection molding machine according to one preferred melt blendingmethod. The original mixture included 3.40 g SAFOAM. When half of theSAFOAM appeared to have been consumed, 3.40 g more was added. Another7.20 g of SAFOAM was added when half of the SAFOAM again appeared tohave been consumed. Temperatures along the injection molding screwranged from about 280° F. at the point of insertion to about 240° F. atthe nozzle. The material of Example 12 had closed cells of fairlyconsistent density.

EXAMPLE

    ______________________________________                                        Component     Generic Class                                                                             Amount (grams)                                      ______________________________________                                        Septon 4055   A-B-A copolymer                                                                           227.0                                               Duoprime 500 oil                                                                            Plasticizing oil                                                                          2,722.0                                             Irganox 1010  Antioxidant 1.5                                                 Irgafos 168   Antioxidant 1.5                                                 Expancell DE-80                                                                             Microspheres                                                                              500.O                                               Orange        Colorant    2.0                                                 ______________________________________                                    

Applicant has also used microspheres to reduce the specific gravity ofthe preferred elastomeric gel cushioning medium. Acrylic microsphereswere used in the material of Example 13. The components were premixed,then compounded in an injection molding machine screw. Temperaturesalong the injection molding screw ranged from about 260° F. at the pointof insertion to about 220° F. at the nozzle. Surprisingly, themicrospheres were not deformed by the high shear and high temperaturesof the injection molding machine. The resulting material was very light,with microspheres consistently dispersed therethrough.

EXAMPLE

    ______________________________________                                        Component     Generic Class                                                                             Amount (grams)                                      ______________________________________                                        Septon 4055   A-B-A copolymer                                                                           114.0                                               Kraton G-1701 A-B copolymer                                                                             5.8                                                 Regalrez 1018 Plasticizing resin                                                                        340.0                                               Edelex 45     Plasticizing oil                                                                          225.0                                               Talc          Talc        20.4                                                Vestenamer 8012                                                                             Tor rubber  11.5                                                Expancell DU-80                                                                             Microspheres                                                                              0.5                                                 Safoam FP-40  Foaming agent                                                                             10.0                                                Irganox 1010  Antioxidant 3.0                                                 Irgafos 168   Antioxidant 3.0                                                 Boiled Linseed Oil        8.0                                                 Green         Colorant    2.0                                                 ______________________________________                                    

In the material of Example 14, Applicant used KRATON® G-1701,manufactured by Shell Chemical Co., to reduce oil bleed. REGALREZ® 1018was used as a plasiticizer and to reduce oil bleed from the material.Talc was included in the material of Example 14 to act as a nucleatingagent during foaming of the material. Since talc migrates to the surfaceof the material, it is also useful as a surface detackifier. Talc mayalso be used as a filler in the material. VESTENAMER 8012, sold by HulsAmerica Inc. of Piscataway, N.J., is a transpolyoctylene rubber (tor)which is useful for reducing oil bleed and reducing melt viscosity ofthe preferred elastomeric gel material. Boiled linseed oil is believedto reduce the melt viscosity and tackiness of the material and toaccelerate the migration of particulate matter to the material'ssurface. Applicant used both microspheres and foaming agents in thematerial of Example 14. Although acrylic microspheres reduce thespecific gravity of the preferred elastomeric gel material, theyincrease the stiffness of the material, though not as much as glass,ceramic, or other rigid microspheres would.

The closed cell foaming and the microsphere dispersion of the materialof Example 14 were consistent. The material was soft and light-weight.The components were well compounded. In addition, the material ofExample 14 did not have an oily feel and exhibited no plasticizerbleedout at room temperature.

Additives such as colorants, flame retardants, detackifiers and otheradditives may be included in the preferred elastomeric gel cushioningmedium. Various formulations of the preferred elastomeric gel materialmay be tailored to achieve differing levels of softness, strength,tackiness and specific gravity as desired. Examples 1 through 11illustrate the surprisingly high elongation and tensile strength of thematerial. Many embodiments of the preferred elastomeric material, ofwhich the preceding examples are representative, exhibit physicalproperties vastly superior to those of John Y. Chen's material, whichApplicant believes to be the closest and best prior art. A chemicalexplanation for the superior results is provided below.

Examples 15 through 35 are other formulations of the preferredelastomeric gel cushioning medium for use in the cushions according tothe present invention. The formulations of Examples 15 through 35 werecompounded using a ZE25 TIEBAR AIR COOLED TWIN SCREW EXTRUDER with a35:1 L/D ratio according to a preferred melt blending method.Temperatures along the screws were in the range of about 130° C. toabout 170° C. at the hopper to about 100° C. to about 130° C. at thenozzle.

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              50.04                                             LP-150       Plasticizing oil                                                                             250.0                                             Irganox 1010 Antioxidant    1.5                                               Irgafos 168  Antioxidant    1.5                                               ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              83.25                                             LP-150       Plasticizing oil                                                                             250.00                                            Irganox 10100                                                                              Antioxidant    1.5                                               Irgafos 168  Antioxidant    1.5                                               ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              50.04                                             Kadol        Plasticizing oil                                                                             250.00                                            E 17         Antioxidant (vitamin E)                                                                      6.26                                              ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              250.00                                            Duoprime 90  Plasticizing oil                                                                             1,250.00                                          E 17         Antioxidant (vitamin E)                                                                      6.30                                              ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              250.00                                            LP-150       Plasticizing oil                                                                             1,250.00                                          E 17         Antioxidant (vitamin E)                                                                      6.25                                              ______________________________________                                    

EXAMPLE

    ______________________________________                                        Component    Generic Class  Amount (grams)                                    ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              350.00                                            Regalrez 1018                                                                              Plasticizing resin                                                                           262.51                                            C23 to C27 Alkane Wax                                                                      Plasticizer    35.00                                             LP-150       Plasticizing oil                                                                             287.60                                            E 17         Antioxidant (vitamin E)                                                                      14.00                                             Ethosperse                  52.50                                             White        Colorant       10.50                                             Yellow       Colorant       0.70                                              Red          Colorant       0.03                                              ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             11.89                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.24                                            LP-150 mineral oil                                                                         Plasticizer      73.87                                           Astor Slack Wax 2050                                                                       Plasticizer      8.33                                            Alkane Wax C 25-27                                                                         Plasticizer      0.59                                            IRGANOX ® 1010                                                                         Antioxidant      0.42                                            IRGAFOS ® 168                                                                          Antioxidant      0.42                                            IRGANOX ® E 17                                                                         Antioxidant      0.42                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.19                                            PQ 6546      Acrylic Microspheres                                                                           1.44                                            Rocket Red   Colorant         1.19                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             14.86                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.30                                            LP-150 mineral oil                                                                         Plasticizer      71.01                                           Astor Slack Wax 2050                                                                       Plasticizer      6.69                                            Alkane Wax C 25-27                                                                         Plasticizer      0.58                                            IRGANOX ® 1010                                                                         Antioxidant      0.52                                            IRGAFOS ® 168                                                                          Antioxidant      0.52                                            IRGANOX ® E 17                                                                         Antioxidant      0.52                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.34                                            PQ 6546      Acrylic Microspheres                                                                           1.44                                            Rocket Red   Colorant         2.23                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             16.66                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.33                                            LP-150 mineral oil                                                                         Plasticizer      67.48                                           Astor Slack Wax 2050                                                                       Plasticizer      7.50                                            Alkane Wax C 25-27                                                                         Plasticizer      0.67                                            IRGANOX ® 1010                                                                         Antioxidant      0.58                                            IRGAFOS ® 168                                                                          Antioxidant      0.58                                            IRGANOX ® E 17                                                                         Antioxidant      0.58                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.50                                            PQ 6546      Acrylic Microspheres                                                                           1.62                                            Rocket Red   Colorant         2.50                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             13.18                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.26                                            LP-150 mineral oil                                                                         Plasticizer      75.12                                           Astor Slack Wax 2050                                                                       Plasticizer      5.27                                            Alkane Wax C 25-27                                                                         Plasticizer      0.33                                            IRGANOX ® 1010                                                                         Antioxidant      0.46                                            IRGAFOS ® 168                                                                          Antioxidant      0.46                                            IRGANOX ® E 17                                                                         Antioxidant      0.46                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.19                                            PQ 6546      Acrylic Microspheres                                                                           1.62                                            Horizon Blue Colorant         1.65                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             11.07                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.22                                            LP-150 mineral oil                                                                         Plasticizer      76.89                                           Astor Slack Wax 2050                                                                       Plasticizer      5.54                                            Alkane Wax C 25-27                                                                         Plasticizer      0.55                                            IRGANOX ® 1010                                                                         Antioxidant      0.39                                            IRGAFOS ® 168                                                                          Antioxidant      0.39                                            IRGANOX ® E 17                                                                         Antioxidant      0.39                                            Amyl Formate (supplied                                                                     Clarity enhancer 0.55                                            by Aldrich)                                                                   TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.66                                            PQ 6546      Acrylic Microspheres                                                                           0.97                                            Horizon Blue Colorant         1.38                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             14.40                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.29                                            LP-150 mineral oil                                                                         Plasticizer      74.50                                           Astor Slack Wax 2050                                                                       Plasticizer      4.80                                            Alkane Wax C 25-27                                                                         Plasticizer      0.50                                            IRGANOX ® 1010                                                                         Antioxidant      0.50                                            IRGAFOS ® 168                                                                          Antioxidant      0.50                                            IRGANOX ® E 17                                                                         Antioxidant      0.50                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.44                                            PQ 6546      Acrylic Microspheres                                                                           0.97                                            Signal Green Colorant         1.58                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             13.37                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.27                                            LP-150 mineral oil                                                                         Plasticizer      74.88                                           Astor Slack Wax 2050                                                                       Plasticizer      5.35                                            Alkane Wax C 25-27                                                                         Plasticizer      3.34                                            IRGANOX ® 1010                                                                         Antioxidant      0.47                                            IRGAFOS ® 168                                                                          Antioxidant      0.47                                            IRGANOX ® E 17                                                                         Antioxidant      0.47                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.34                                            Amyl Formate Clarity Enhancer 0.40                                            PQ 6546      Acrylic Microspheres                                                                           0.99                                            Signal Green Colorant         1.47                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             8.14                                            KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.16                                            LP-150 mineral oil                                                                         Plasticizer      80.76                                           Astor Slack Wax 2050                                                                       Plasticizer      6.51                                            Alkane Wax C 25-27                                                                         Plasticizer      0.49                                            IRGANOX ® 1010                                                                         Antioxidant      0.28                                            IRGAFOS ® 168                                                                          Antioxidant      0.28                                            IRGANOX ® E 17                                                                         Antioxidant      0.28                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.22                                            PQ 6546      Acrylic Microspheres                                                                           0.97                                            Blaze Orange Colorant         0.90                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             8.12                                            KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.16                                            LP-150 mineral oil                                                                         Plasticizer      80.60                                           Astor Slack Wax 2050                                                                       Plasticizer      6.50                                            Alkane Wax C 25-27                                                                         Plasticizer      0.49                                            IRGANOX ® 1010                                                                         Antioxidant      0.28                                            IRGAFOS ® 168                                                                          Antioxidant      0.28                                            IRGANOX ® E 17                                                                         Antioxidant      0.28                                            TETRAGLYME   Anti-bleed, anti-tack additive                                                                 1.22                                            Amyl Formate Clarity Enhancer 0.20                                            PQ 6546      Acrylic Microspheres                                                                           0.97                                            Blaze Orange Colorant         0.90                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             12.10                                           KRATON ® G 1701                                                                        Diblock copolymer                                                                              0.30                                            LP-150 mineral oil                                                                         Plasticizer      84.47                                           IRGANOX ® 1010                                                                         Antioxidant      0.18                                            IRGAFOS ® 168                                                                          Antioxidant      0.18                                            FC-10 fluorochemical                                                                       Bleed-reducing additive                                                                        0.18                                            alcohol                                                                       Strong Magenta                                                                             Colorant         0.36                                            Horizon Blue Colorant         0.36                                            PQ 6545      Acrylic Microspheres                                                                           1.62                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             19.69                                           LP-150 mineral oil                                                                         Plasticizer      78.78                                           IRGANOX ® 1010                                                                         Antioxidant      0.20                                            IRGAFOS ® 168                                                                          Antioxidant      0.20                                            DYNAMAR ® FX 9613                                                                      Bleed-reducing additive                                                                        0.15                                            091DU80      Acrylic Microspheres                                                                           0.98                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             19.60                                           LP-150 mineral oil                                                                         Plasticizer      78.39                                           IRGANOX ® 1010                                                                         Antioxidant      0.19                                            IRGAFOS ® 168                                                                          Antioxidant      0.20                                            DYNAMAR ® FX 9613                                                                      Bleed-reducing additive                                                                        0.15                                            091DU80      Acrylic Microspheres                                                                           1.47                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             28.38                                           LP-150 mineral oil                                                                         Plasticizer      70.92                                           IRGANOX ® 1010                                                                         Antioxidant      0.28                                            IRGAFOS ® 168                                                                          Antioxidant      0.28                                            ZONYL ® BA-N                                                                           Bleed-reducing additive                                                                        0.14                                            ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             23.43                                           LP-150 mineral oil                                                                         Plasticizer      58.55                                           IRGANOX ® 1010                                                                         Antioxidant      0.23                                            IRGAFOS ® 168                                                                          Antioxidant      0.23                                            Carbowax     Plasticizer, includes polar                                                                    17.56                                                        molecules                                                        ______________________________________                                    

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        SEPTON ® 4055                                                                          Triblock copolymer                                                                             15.14                                           SEPTON ® 4033                                                                          Triblock copolymer                                                                             3.79                                            LP-150 mineral oil                                                                         Plasticizer      80.45                                           IRGANOX ® 1010                                                                         Antioxidant      0.19                                            IRGAFOS ® 168                                                                          Antioxidant      0.19                                            ZONYL ® BA-N                                                                           Bleed-reducing additive                                                                        0.15                                            Horizon Blue Colorant         0.09                                            ______________________________________                                    

6. Representative Visco-Elastomeric Gel Formulations

The following examples have been prepared by Applicant.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4055  A-B-A copolymer  5.46                                            Kraton G1701 A-B copolymer    0.55                                            Irganox 1010 antioxidant      0.16                                            Irgafos 168  antioxidant      0.16                                            LP-150       plasticizing oil 32.77                                           Regalrez 1018                                                                              plasticizing resin                                                                             54.62                                           Kristalex 5140                                                                             strengthening resin                                                                            0.55                                            Regalite R101                                                                              plasticizing resin                                                                             2.73                                            Regalrez 1139                                                                              plasticizimg resin                                                                             2.73                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.16                                                         and decrease specific gravity                                    Bright orange                                                                              colorant         0.11                                            aluminum lake                                                                 ______________________________________                                    

SEPTON® 4055 imparts form and strength to the visco-elastic material.KRATON® G-1701 is used to facilitate a more homogeneous blend of theelastomer (A-B-A copolymer) and plasticizer components. REGALREZ® 1018,a room temperature liquid plasticizer, is the primary plasticizer usedin the material. REGALITE® R101 and REGALREZ® 1139 are also plasticizersand modify the tack of the visco-elastic material. KRISTALEX® 5140 isbelieved to impart strength to the styrene domains or centers of theA-B-A copolymer. It is also believed to have some plasticizing abilitieswhen used in combination with A-B-A copolymers. IRGANOX® 1010 andIRGAFOS® 168 are antioxidants. The material of Example 36 was made as anearly experiment. Consequently, LP-150, a plasticizing oil, was used incombination with the resin plasticizers.

The material of Example 36 was prepared by premixing the components andmelt blending them in an injection molding machine according to onepreferred method for compounding the preferred gel cushioning medium.The material was very tacky and readily deformable, had very quickrebound and was very soft. Applicant believes that the very quickrebound rate is caused by the presence of plasticizing oil andmicrospheres. The specific gravity of the material was about 0.40.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 8006  A-B-A copolymer  2.42                                            Septon 4055  A-B-A copolymer  2.42                                            Kraton 01701 A-B copolymer    0.48                                            Irganox 1010 antioxidant      0.15                                            Irgafos 168  antioxidant      0.15                                            Regafrez 1018                                                                              plasticizing resin                                                                             87.18                                           Kristalex 5140                                                                             strengthening resin                                                                            0.48                                            Regalite R101                                                                              plasticizing resin                                                                             2.42                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.42                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 1.39                                                         and decrease specific gravity                                    Bright orange                                                                              colorant         0.24                                            aluminum lake                                                                 Dow Corning 200                                                                            rubber additive  0.24                                            silicone                                                                      ______________________________________                                    

In the material of Example 37, SEPTON® 8006 was used in combination withSEPTON® 4055 to provide some form, but a softer visco-elastic material.Silicone was added to detackify the material.

The material of Example 37 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred method for compounding the preferred gel material. Thematerial was slightly tacky and readily deformable, had slow rebound andmoderate stiffness. The use of silicone seems to have decreased thetackiness of the material. The specific gravity of the material wasabout 0.30.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 8006  A-B-A copolymer  2.45                                            Septon 4055  A-B-A copolymer  2.45                                            Kraton G1701 A-B copolymer    0.49                                            Irganox 1010 antioxidant      0.15                                            Irgafos 168  antioxidant      0.15                                            Regalrez 1018                                                                              plasticizing resin                                                                             88.38                                           Kristalex 5140                                                                             strengthening resin                                                                            0.49                                            Regalite R101                                                                              plasticizing resin                                                                             2.46                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.46                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.28                                                         and decrease specific gravity                                    Bright orange                                                                              colorant         0.25                                            aluminum lake                                                                 ______________________________________                                    

The material of Example 38 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred method for compounding the preferred gel material for use inthe cushions of the present invention. The material was very tacky andreadily deformable, had a slow to moderate rebound rate and wasextremely soft. The specific gravity of the material was about 0.65.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 8006  A-B-A copolymer  2.45                                            Septon 4055  A-B-A copolymer  2.45                                            Kraton G1701 A-B copolymer    0.49                                            Irganox 1010 antioxidant      0.15                                            Irgafos 168  antioxidant      0.15                                            Regalrez 1018                                                                              plasticizing resin                                                                             88.06                                           Kristalex 5140                                                                             strengthening resin                                                                            0.49                                            Regalite R101                                                                              plasticizing resin                                                                             2.45                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.45                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.64                                                         and decrease specific gravity                                    Bright orange                                                                              colorant         0.24                                            aluminum lake                                                                 ______________________________________                                    

The material of Example 39 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was very tacky and readilydeformable, had moderate rebound and moderate softness. The specificgravity of the material was about 0.44.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 8006  A-B-A copolymer  2.43                                            Septon 4055  A-B-A copolymer  2.43                                            Kraton G1701 A-B copolymer    0.49                                            Irganox 1010 antioxidant      0.15                                            Irgafos 168  antioxidant      0.15                                            Regalrez 1018                                                                              plasticizing resin                                                                             87.51                                           Kristalex 5140                                                                             strengthening resin                                                                            0.49                                            Regalite R101                                                                              plasticizing resin                                                                             2.43                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.43                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 1.26                                                         and decrease specific gravity                                    Bright orange                                                                              colorant         0.24                                            aluminum lake                                                                 ______________________________________                                    

The material of Example 40 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was tacky and readilydeformable, had very quick rebound and moderate softness. The specificgravity of the material was about 0.28.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 8006  A-B-A copolymer  2.44                                            Septon 4055  A-B-A copolymer  2.44                                            Kraton G1701 A-B copolymer    0.49                                            Irganox 1010 antioxidant      0.15                                            Irgafos 168  antioxidant      0.15                                            Regalrez 1018                                                                              plasticizing resin                                                                             87.78                                           Kristalex 5140                                                                             strengthening resin                                                                            0.49                                            Regalite R101                                                                              plasticizing resin                                                                             2.44                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.44                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.95                                                         and decrease specific gravity                                    Colorant - bright             0.24                                            orange aluminum lake                                                          ______________________________________                                    

The material of Example 41 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was very tacky and readilydeformable, had slow rebound and little stiffness. The specific gravityof the material was about 0.37.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4003  A-B-A copolymer  0.29                                            Septon 8006  A-B-A copolymer  4.05                                            Kraton G1701 A-B copolymer    0.09                                            Irganox 1010 antioxidant      0.12                                            Irgafos 168  antioxidant      0.12                                            Regalrez 1018                                                                              plasticizing resin                                                                             86.73                                           Kristalex 5140                                                                             plasticizing resin                                                                             0.87                                            Regalite R101                                                                              plasticizing resin                                                                             2.02                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.02                                            Vistanex LM-MS                                                                             plasticizing resin                                                                             2.89                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.37                                                         and decrease specific gravity                                    Safoam FP-powder                                                                           blowing agent    0.43                                            ______________________________________                                    

In the material of Example 42, SEPTON® 4033 was used as a lowermolecular weight polymer to help trap foam bubbles. A greater weightpercentage of SEPTON® 8006 was used to provide a visco-elastomericmaterial which was softer than the materials of the preceding examples.VISTANEX® LM-MS was also added to determine whether its presenceimproved the material's ability to retain foam bubbles.

In preparing the material of Example 42, the solid resins were firstcrushed and premixed. The VISTANEX® LM-MS was heated for thirty minutesin an oven at about 150 to 200° C. The REGALREZ® and VISTANEX® were thenmixed together with heat until the VISTANEX® appeared to be completelysolvated.

The components of the material of Example 42 were then melt blended inan injection molding machine according to a preferred compoundingmethod. The material was very tacky and readily deformable, had veryslow rebound and was very soft. The use of VISTANEX® LM-MS appears tohave decreased the rebound rate of the material. The specific gravity ofthe material was about 0.61.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4003  A-B-A copolymer  0.29                                            Septon 8006  A-B-A copolymer  4.05                                            Kraton G1701 A-B copolymer    0.09                                            Irganox 1010 antioxidant      0.12                                            Irgafos 168  antioxidant      0.12                                            Vistanex LM-MS                                                                             plasticizing resin                                                                             2.90                                            Regalrez 1018                                                                              plasticizing resin                                                                             86.85                                           Kristalex 5140                                                                             strengthening resin                                                                            0.87                                            Regalite R101                                                                              plasticizing resin                                                                             2.03                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.03                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.67                                                         and decrease specific gravity                                    ______________________________________                                    

In preparing the material of Example 43,the crystallized (not readilyflowable at room temperature) resins were first crushed and premixed.The VISTANEX® LM-MS was heated for thirty minutes in oven at about 150to 200° C. The REGALREZ® and VISTANEX® were then mixed together withheat until the VISTANEX® appeared to be completely solvated.

The components of the material of Example 43 were then melt blended inan injection molding machine according to a preferred method forcompounding the preferred gel cushioning media. The material was verytacky and readily deformable, had extremely slow, incomplete rebound andwas very soft. The specific gravity of the material was about 0.47.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4077  A-B-A copolymer  4.67                                            Irganox 1010 antioxidant      0.30                                            Irgafos 168  antioxidant      0.30                                            Regalrez 1018                                                                              plasticizing resin                                                                             83.25                                           Vistanex LM-MS                                                                             plasticizing resin                                                                             1.81                                            Kristalex 5140                                                                             plasticizing resin                                                                             0.96                                            Regalite R101                                                                              plasticizing resin                                                                             1.93                                            Regalrez 1139                                                                              plasticizing resin                                                                             1.93                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.60                                                         and decrease specific gravity                                    Glycerin     detackifying agent                                                                             4.25                                            ______________________________________                                    

SEPTON® 4077 was included in the material of Example 44 to provide formand strength to the material, yet provide a softer material than thatusing SEPTON® 4055. The crystallized (not readily flowable at roomtemperature) resins of Example 44 were first crushed and premixed. TheVISTANEX® LM-MS was heated for thirty minutes in oven at about 150 to200° C. The REGALREZ® and VISTANEX® were then mixed together with heatuntil the VISTANEX® appeared to be completely solvated.

The remaining components were then quickly mixed and melt blended in aninjection molding machine according to a preferred compounding method.The material was very tacky (but less than a comparable material withoutthe glycerin), readily deformable, had extremely slow, incompleterebound and moderate softness. Use of SEPTON® 4077 appears to haveresulted in a material which is softer than those which include SEPTON®4055 as the only plasticizer, but stiffer than materials of the previousexamples which have a combination of copolymers. The specific gravity ofthe material was about 0.40.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4077  A-B-A copolymer  4.67                                            Irganox 1010 antioxidant      0.30                                            Irgafos 168  antioxidant      0.30                                            Regalrez 1018                                                                              plasticizing resin                                                                             83.25                                           Vistanex LM-MS                                                                             plasticizing resin                                                                             1.81                                            Kristalex 5140                                                                             strengthening resin                                                                            0.96                                            Regalite R101                                                                              plasticizing resin                                                                             1.93                                            Regalrez 1139                                                                              plasticizing resin                                                                             1.93                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.60                                                         and decrease specific gravity                                    Glycerin     detackifying agent                                                                             4.25                                            ______________________________________                                    

Glycerine was added to detackify the material of Example 45. Inpreparing the material of Example 45,the crystallized (not readilyflowable at room temperature) resins were first crushed and premixed.The VISTANEX® LM-MS was heated for thirty minutes in oven at about 150to 200° C. The REGALREZ® and VISTANEX® were then mixed together withheat until the VISTANEX® appeared to be completely solvated.

The remaining components were then mixed thoroughly and melt blended inan injection molding machine according to a preferred compoundingmethod. The material was moderately tacky and readily deformable, hadquick rebound and was soft. Glycerine appears to have reduced thetackiness of the material. The specific gravity of the material wasabout 0.42.

EXAMPLE

    ______________________________________                                                                   Weight %                                           Component     Generic Class                                                                              of Total                                           ______________________________________                                        Septon 4055   A-B-A copolymer                                                                            2.47                                               Septon 8006   A-B-A copolymer                                                                            2.47                                               Kraton G1701  A-B copolymer                                                                              0.49                                               Irganox 1010  antioxidant  0.15                                               Irgafos 168   antioxidant  0.15                                               Regalrez 1018 plasticizing resin                                                                         88.85                                              Kristalex 5140                                                                              strengthening resin                                                                        0.49                                               Regalite R101 plasticizing resin                                                                         2.47                                               Regalrez 1139 plasticizing resin                                                                         2.47                                               ______________________________________                                    

The material of Example 46 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was extremely tacky andreadily deformable, had slow rebound and was very soft. The specificgravity of the material was about 0.37.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4055  A-B-A copolymer  2.35                                            Septon 8006  A-B-A copolymer  2.35                                            Kraton G1701 A-B copolymer    0.47                                            Irganox 1010 antioxidant      0.14                                            Irgafos 168  antioxidant      0.14                                            Regalrez 1018                                                                              plasticizing resin                                                                             84.36                                           Kristalex 5140                                                                             strengthening resin                                                                            0.47                                            Regalite R101                                                                              plasticizing resin                                                                             2.34                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.34                                            PQ 6545 microspheres                                                                       added to increase rebound rate                                                                 0.36                                                         and decrease specific gravity                                    Glycerin     detackifying agent                                                                             4.69                                            ______________________________________                                    

The material of Example 47 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred method for compounding the preferred gel cushioning materialsfor use in the cushioning elements of this invention. The material wasvery tacky and readily deformable, had slow rebound and littlestiffness.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component    Generic Class    of Total                                        ______________________________________                                        Septon 4055  A-B-A copolymer  2.39                                            Septon 8006  A-B-A copolymer  2.39                                            Kraton G1701 A-B copolymer    0.48                                            Irganox 1010 antioxidant      0.14                                            Irgafos 168  antioxidant      0.14                                            Regalrez 1018                                                                              plasticizing resin                                                                             80.21+                                                                        (see premix                                                                   below)                                          Kristalex 5140                                                                             strengthening resin                                                                            0.48                                            Regalite R101                                                                              plasticizing resin                                                                             2.39                                            Regalrez 1139                                                                              plasticizing resin                                                                             2.39                                            Premixed microspheres         9.00                                            PQ 6545 microspheres                                                                       added to increase rebound                                                                      11.76% of                                                    rate and decrease specific                                                                     premix                                                       gravity          (1.06)                                          Regalrez 1018                 88.24% of                                                                     premix                                                                        (7.94)                                          ______________________________________                                    

The material of Example 48 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was extremely tacky andreadily deformable, had slow rebound and little stiffness. The specificgravity of the Example 48 material was about 0.63.

Pre-blending the microspheres with REGALREZ® 1018 was, in part,advantageous because it reduced the amount of microspheres that weredispersed into the air during agitation, making the microspheres easierto handle.

EXAMPLE 49

A visco-elastic material was made which included four parts REGALREZ®1018 (plasticizing resin), four parts HERCULES® Ester Gum 10D(plasticizing resin) and one part SEPTON 4055 (A-B-A copolymer). Thecomponents were mixed, placed in an oven and heated to about 300° F.After all of the components became molten, they were mixed, poured ontoa flat surface and cooled. The material had little tack, deformed underpressure, was very stiff but readily deformable with light sustainedpressure, and had an extremely slow rate of rebound.

EXAMPLE

    ______________________________________                                                                      Weight %                                        Component      Generic Class  of Total                                        ______________________________________                                        Septon 4055    A-B-A copolymer                                                                              11.75                                           Ester Gum 10D  visco-elasticity enhancer                                                                    35.25                                           Regalrez 1018  plasticizing resin                                                                           29.38                                           Kristalex 5140 strengthening resin                                                                          1.18                                            Foral 85       strengthening resin                                                                          3.53                                            LP-150 oil     plasticizing oil                                                                             14.10                                           Ethosperse LA-23                                                                             foaming facilitator                                                                          3.53                                            Irganox 1010   antioxidant    0.35                                            Irgafos 168    antioxidant    0.35                                            Aluminum Lake Colorant        0.59                                            (Rocket red)                                                                  ______________________________________                                    

The material of Example 50 was prepared by premixing the components andmelt blending them in an injection molding machine according to apreferred compounding method. The material was moderately tacky anddeformable under slight, prolonged compressive force, had extremely slowrebound and was very stiff.

FORAL 85, manufactured by Hercules, is a glycerol ester of hydrogenatedresin that is used primarily as a tackifier. In the preferredvisco-elastic gel, FORAL 85 acts as a strengthening resin, and isbelieved to associate with and bind together the styrene domains.ETHOSPERSE LA-23, known generically in the art as Laureth-23, is used inthe art as an emulsifier. Laureth-23 facilitates foaming in the gelmaterials preferred for use in the cushions of the present invention.The other components of Example 50 have been explained above.

EXAMPLE

    ______________________________________                                                                    Weight %                                          Component    Generic Class  of Total                                          ______________________________________                                        Septon 4055  A-B-A copolymer                                                                              80.00                                             Septon 4077  A-B-A copolymer                                                                              80.00                                             Kraton G-1701                                                                              A-B copolymer  16.00                                             Regalrez 1018                                                                              plasticizing resin                                                                           2688.00+                                                                (see microsphere                                                              premix below)                                           Irganox 1010 antioxidant    4.80                                              Irgafos 168  antioxidant    4.80                                              Premixed microspheres       402.30                                            PQ 6545 microspheres                                                                       added to increase                                                                            11.76% of premix                                               rebound rate and                                                                              (47.31 g)                                                     decrease specific gravity                                        Regalrez 1018               88.24% of premix                                                              (354.99 g)                                        ______________________________________                                    

The material of Example 51 was prepared by preheating the REGALREZ®1018, mixing all of the components except the microspheres together, andmelt blending the components in a heated vessel at 295° F. under aboutone to about four pounds pressure for about two hours, according to acompounding method of the present invention. The mixture was thentransferred to another vessel, which was heated to about 300° F., andthe premixed microspheres and REGALREZ® 1018 were mixed in by hand.

The material was very tacky and readily deformable, had moderately slowrebound and was very soft. The specific gravity of the material ofExample 51 was about 0.51.

Of the preceding sixteen examples (Examples 36-51), Applicant preferredthe material of Example 51 because of its extreme softness and slow tomoderate rebound rate. Applicant also liked the material of Example 50because of its stiffness, but easy deformability under sustainedpressure, and its extremely slow rate of reformation.

EXAMPLE 52

A visco-elastic material which includes from about one to about 30weight percent of a triblock copolymer and about 70 to about 99 weightpercent of a plasticizer, said weight percentages being based upon thetotal weight of the visco-elastic material. The visco-elastic materialmay also include up to about 2.5 weight percent of a primary antioxidantand up to about 2.5 weight percent of a secondary antioxidant, saidweight percentages based upon the weight of the triblock copolymer.

Although the gel formulations referred to above are most preferred,there are numerous other preferred gels. For example, although theyexhibit less desirable characteristics than the preferred gel cushioningmedia, the gel formulations of the following U.S. Patent Nos. are alsouseful in the cushions of the present invention: U.S. Pat. Nos.5,334,646, issued in the name of John Y. Chen; 4,369,284, issued in thename of John Y. Chen; 5,262,468, issued in the name of John Y. Chen;4,618,213, issued in the name of John Y. Chen; 5,336,708, issued in thename of John Y. Chen, each of which is incorporated by reference in itsentirety. Other oil-extendedpolystyrene-poly(ethylene/butylene)-polystyrene gels can be usedadvantageously for the cushions of this invention. For example, the GLSCorporation of Cary, Ill. offers a gel in injection moldable pellet formunder the designation G-6703 which is made with the ingredients of thegels mentioned above but with less plasticizing oil, and has a Shore Ahardness of 3. Other preferred gels which may be used in the inventioninclude PVC plastisol gels, silicone gels, and polyurethane gels.

PVC plastisol gels are well known in the art, and are exemplified byartificial worms and grubs used in fishing. A description of a typicalPVC plastisol gel is given in U.S. Pat. No. 5,330,249 issued in the nameof Weber et al. on Jul. 19, 1994, which is hereby incorporated byreference. PVC plastisol gels are not the most preferred because theirstrength is not as high for a given gel rigidity as the preferred gelmedia or even the gels of the Chen patents, but they are acceptable foruse in the invention.

Silicone gels are also well known in the art, and are available frommany sources including GE Silicones and Dow Corning. From a performancestandpoint, silicone gels are excellent for use in this invention.However, the cost of silicone gels is many times higher than that of themost preferred gels.

Polyurethane gels are also well known in the art, and are available froma number of companies including Bayer Aktiengesellschaft in Europe. Forreference, the reader is directed to U.S. Pat. No. 5,362,834 issued inthe name of Schapel et al. on Nov. 8, 1994, which is hereby incorporatedby reference, for more information concerning polyurethane gels. Likesilicone gels, polyurethane gels are excellent from a performancestandpoint, but are many times more expensive than the most preferredgels.

Foam rubber and polyurethane foams may also be useful as cushioningmedia in the cushioning elements of the present invention, so long asthey exhibit gel-like buckling behavior. Preferably, in order to exhibitdesired buckling and elastomeric or visco-elastomeric gel-like behavior,column walls formed from polyurethane foams and foam rubbers are verythin. Alternatively, thicker column walls formed from polyurethane foamsand foam rubbers may also exhibit the desired buckling and gel-likecharacteristics with appropriate column shapes and column patternconfigurations. Foam rubbers and polyurethane foams are useful in thecushioning element of the present invention if columns occupy aboutone-half or more of the cushion volume. Cushion volume is defined by thetop and bottom surfaces and the perimeter of the cushion.

C. Method for Making the Cushions

There are several ways in which the cushion can be manufactured.

1. Injection Molding

The invented cushions can be injection molded by standard injectionmolding techniques. For example, a cavity mold is created with coresinside the cavity. The gel ingredients are heated while stirring, whichturns the gel into a liquid. The liquid is injected into the cavity andflows around the cores. The material is allowed to cool, which causes itto solidify. When the mold is parted, the cores pull out of thesolidified gel and leave the hollow columns. The cushion is removed fromthe cavity, the mold is closed, and liquid is injected to form the nextcushion, this process being repeated to manufacture the desired quantityof cushioning elements. This results in very inexpensive cushioningelements because the preferred gel is inexpensive and the manufacturingprocess is quick and requires very little labor.

Referring to FIG. 4, an example mold in use is depicted. The moldassembly 401 has a first mold half 401 and a second mold half 404. Thesecond mold half 404 has a cavity 408 and a base plate 405 at the bottomof the cavity 408. It also has side walls 414 and 415. The first moldhalf 402 has a core mounting plate 409 and a plurality of cores 403mounted on it in any desired spacing and arrangement. The cores 403 maybe of any desired shape, such as triangular, square, pentagonal, n-sided(where n is any integer), round, oval or of any other configuration incross section in order to yield a molded cushioning element 406 of thedesired configuration. The cores 403 could also be tapered from a morenarrow dimension (reference numeral 410) at their end distal from thecore mounting plate 409 to a wider dimension (reference numeral 411) attheir end proximal the core mounting plate. This would create a taperedcolumn or tapered column walls so that the radial measurement of acolumn orthogonal to its longitudinal axis would be different at twoselected different points on the longitudinal axis.

Alternatively, the cores 403 could be tapered from 410 to 411, steppedfrom 410 to 411 or configured otherwise to create a column of desiredshape. Use of the hexagonal cores 403 depicted yields a cushioningelement 406 with cushioning media 412 molded so that the column walls413 form the hollow columns 407 in a hexagonal configuration.

When the first mold half 402 and second mold half 404 are broughttogether, core distal ends 410 abut the second mold half base plate 405.This prevents liquid cushioning media from flowing between the baseplate 405 and the core distal ends 410 in order to achieve a cushioningelement 406 which has hollow columns through which air can circulate. Ifthe core distal ends 410 did not reach all the way to the base plate408, then the columns 407 would be open at one end and closed at theother.

FIG. 5 depicts an alternative mold configuration. The mold assembly 501includes first mold half 502 that includes a first core mounting plate509 onto which a plurality of cores 503 are mounted in a desiredconfiguration. The cores 503 each have a core proximal end proximal tothe core mounting plate 509 and a core distal end 511 distal to the coremounting plate 509. The mold assembly 501 also includes a mold secondhalf 504 which has a core mounting plate 505, side walls 512, and cores508 each having a core proximal end 513 proximal to the core mountingplate 505 and a core distal end 514 distal to the core mounting plate.The second core half 504 also has a cavity 514 in which its cores 508are found. The mold assembly 501 may be designed so that when the twomold halves are brought together the core distal ends abut the surfaceof their opposing core mounting plates. This produces a cushioningelement 506 with hollow columns 507 that are open from one end to theother in order to maximize air circulation through the columns 507 andyieldability of the cushioning element 506. Alternatively, the moldassembly 501 may be designed so that the core distal ends do not contactthe core mounting plates. This will result in a cushion having a crosssectional appearance like that depicted in FIG. 6, where the columns areshorter in length than the thickness of the cushioning element, so thecolumns are closed at one end.

2. Extrusion

The invented cushioning elements may also be manufactured by typicalextrusion processes. If extrusion is used, hot liquid gel is forcedthrough an extrusion die. The die has metal rods situated to obstructthe path of the gel in some locations so that the gel is forced throughthe die in a pattern resembling the desired shape of the finishedcushioning element. Thus the die, having an aperture, an apertureperiphery, and forming rods within the aperture has an appearancesimilar to that of the desired cushioning element except that theportions of the die that are solid will be represented by empty air inthe finished cushion, and the portions of the die in the aperture thatare unobstructed will represent gel in the finished cushioning element.Thus the rods of the die should be of the shape and size that thedesired cushioning element is intended to be; the spacing of the rodsshould approximate the spacing of the columns that is desired in thefinished cushioning element; and the shape and size of the apertureperiphery should approximate the shape and size of the periphery of thedesired cushioning element.

When gel is forced through the die, the liquid gel is cooled during itstraverse through the die, causing it to solidify as it leaves the die.The gel is then cut at desired length intervals to form cushioningelements. Of course, cushioning elements so formed have hollow columnsthroughout their length, although the ends of the columns could besealed as mentioned elsewhere herein. It is not expected, however, thatextrusion is a practical method for manufacturing cushions with columnsthat vary in dimension along their length. The extruded cushioningelement is very inexpensive because the both the cushioning media (i.e.the preferred gel) is inexpensive and the manufacturing process ishighly automated so that labor requirements are very low.

Alternatively, a single tube may be extruded, then cut to a length thatwill form the appropriate cushion thickness. The tubes are then bondedtogether to form a cushioning element according to the presentinvention. Referring to FIG. 41, a preferred embodiment of a cushion4101 which is made from bonded tubes 4102a, 4102b, 4102c, etc. is shown.Each tube includes a hollow column 4103 formed by a column wall 4104.Preferably, column wall 4104 is made from a gel cushioning medium 4105,such as the preferred elastomeric or visco-elastomeric materials for usein the cushions of the present invention.

FIG. 42 illustrates an example of a preferred method for bonding twotubes 4102a and 4102b together. Heating cores 4201 and 4203, whichpreferably include a heating edge 4202 and 4204, respectively, arepositioned in tubes 4102a and 4102b within corners 4110a and 4110b,respectively, such that edges 4202 and 4204 abut the inner surface ofthe corners. Preferably, cores 4201 and 4203 hold the outer surface ofcorners 4110a and 4110b against one another. Preferably, securing cores4205 and 4206 are positioned in each of the two inner corners formed bytubes 4102a and 4102b to secure corners 4110a and 4110b from slidingside-to-side in relation to one another. Preferably, heating edges 4202and 4204 are heated to a temperature sufficient to melt cushioningmedium 4105, but not to a temperature which would burn the material. Asheating edges 4202 and 4204 are heated to a desirable temperature, thecushioning medium located in corners 4110a and 4110b melts. Preferably,heating edges 4202 and 4204 remain heated until all of the materiallocated at corners 4110a and 4110b becomes molten and fuses tubes 4102aand 4102b together. Heating edges 4202 and 4204 and corners 4110a and4110b are then cooled. Preferably, heating edges 4202 and 4204 are eachcovered with a non-stick surface 4207 and 4208, respectively. Similarly,securing cores 4205 and 4206 also have non-stick surfaces 4211 and 4212.The non-stick surfaces prevent the securing cores 4205 and 4206 andheating edges 4202 and 4204 of heating cores 4201 and 4203 from stickingto the cushioning medium located at corners 4110a and 4110b as themedium becomes molten. A preferred non-stick surface is teflon paper.Cores 4201, 4203, 4205 and 4206 are then removed from tubes 4102a and4102b.

3. Casting

Another manufacturing process by which the invented cushioning elementcan be made is by generally known casting technology. In order to castthe invented cushioning element, hot liquid gel (or other cushioningmedia) is poured into an open cavity, and an assembly of metal rods ispushed into the liquid. The rods will form the columns of the finishedproduct. The liquid flows between the metal rods, cools and solidifies.The metal rods are then removed, leaving the hollow portions of thecolumns, and the cushion is removed from the cavity. A vibrator may beused to vibrate the cavity to facilitate the flow of the liquid betweenthe rods if needed.

Casting is a more labor intensive manufacturing method than injectionmolding or extrusion, but the tooling is generally less expensive,especially for large cushions. This is the preferred method of makingvery large cushions, such as king-size bed mattresses, since the size ofsuch cushions is greater than that which can be manufactured usinginjection molding or extrusion methods.

The reader should note that any other manufacturing method may be usedwhich results in a cushioning element having the general configurationof or achieving the object of this invention. Such other methods mayinclude but are not limited to rotational molding of a cushioning mediasuch as a hot liquid gel, and vacuum forming of sheets of a cushioningmedia such as gel.

While the present invention has been described and illustrated inconjunction with a number of specific embodiments, those skilled in theart will appreciate that variations and modifications may be madewithout departing from the principles of the invention as hereinillustrated, described, and claimed.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects as only illustrative,and not restrictive. The scope of the invention is, therefore, indicatedby the appended claims, rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A yieldable cushioning element that includes aflexible, resilient, gel cushioning media having shape memory and beingsubstantially solid and non-flowable at temperatures below 130 degreesFahrenheit, the cushioning element comprising:a quantity of gelcushioning medium formed to have a top, a bottom, and an outerperiphery, said cushioning medium being compressible so that it willdeform under the compressive force of a cushioned object, a plurality ofhollow columns formed in said cushioning medium, each of said columnshaving a longitudinal axis along its length, each of said columns havinga column wall which defines a column interior, and each of said columnshaving two ends; wherein the cushioning element is adapted to have acushioned object placed in contact with said top; wherein each of saidcolumn ends is positioned at two different points of said column axis;wherein at least one of said columns is positioned within saidcushioning medium such that said column axis is positioned generallyparallel to the direction of a compressive force exerted on thecushioning element by a cushioned object in contact with said cushioningmedium; and wherein at least one of said column walls is capable ofbuckling beneath a protuberance that is located on the cushioned object.2. A yieldable cushioning element as recited in claim 1, wherein atleast one other of said columns is positioned within said cushioningmedium such that said column axis is positioned generally non-parallelto the direction of a compressive force exerted on the cushioningelement by the cushioned object in contact with said cushioning medium.3. A yieldable cushioning element as recited in claim 1, wherein atleast one of said column ends of at least one of said columns is open tosaid column interior.
 4. A yieldable cushioning element as recited inclaim 1, wherein both of said column ends of at least one of saidcolumns is open to said column interior.
 5. A yieldable cushioningelement as recited in claim 4, wherein said column interior is hollow sothat air may pass through said column to one of said column ends toventilate a cushioned object in contact with said one column end.
 6. Ayieldable cushioning element as recited in claim 1, wherein said gelcushioning medium is selected from the group consisting of gelatinouselastomers and gelatinous visco-elastomers.
 7. A yieldable cushioningelement as recited in claim 1, wherein said cushioning medium generallyretains its structure at normal useable temperatures of the cushioningelement.
 8. A yieldable cushioning element as recited in claim 1,wherein said cushioning medium does not escape from a puncture on saidcushioning element.
 9. A yieldable cushioning element as recited inclaim 1, wherein a cross section of one of said columns taken orthogonalto said longitudinal axis of said column has a shape selected from thegroup consisting of triangular, square, rectangular, pentagonal,heptagonal, octagonal, round, oval, and n-sided polygonal where n is aninteger.
 10. A yieldable cushioning element as recited in claim 1,wherein said cushioning element has shape memory so that when acushioned object is removed from contact with the cushioning element,the cushioning element has a tendency to return to a shape thatapproximates the shape of the cushioning element before the cushioningelement and the cushioned object came into contact with each other. 11.A yieldable cushioning element as recited in claim 1, wherein thecushioning element is configured to have a low overall thermal mass anda low rate of thermal transfer, compared to the rate of thermal transferof solid gel cushioning elements, in order to provide a comfortablecushioning element.
 12. A yieldable cushioning element as recited inclaim 1, wherein at least one of said columns has a column interior thathas a greater measurement orthogonal to the longitudinal axis of thatcolumn at a first point on the longitudinal axis of the column than at asecond point on said longitudinal axis.
 13. A yieldable cushioningelement as recited in claim 12, wherein said column is tapered betweenthe first of said column ends and the second of said column ends.
 14. Ayieldable cushioning element as recited in claim 12, wherein said columnis stepped between the first of said column ends and the second of saidcolumn ends.
 15. A yieldable cushioning element as recited in claim 1,wherein both ends of at least one column are sealed so that said columninterior is not in direct fluid or gas communication with a regionoutside of said column interior.
 16. A yieldable cushioning element asrecited in claim 15, wherein said column interior contains a quantity offluid cushioning medium therein.
 17. A cushioning element as recited inclaim 1, wherein at least one of said columns has a firmness protrusionlocated at one of said column ends, said firmness protrusion beingadapted to provide support within said column when said column bucklesunder a compressive force so that the cushioning element can readilyyield in the vicinity of said column under a cushioned object until thecushioned object begins to compress said firmness protrusion, whereuponsaid firmness protrusion retards further movement of the cushionedobject into the cushioning element.
 18. A yieldable cushioning elementas recited in claim 1, wherein at least one of said columns is adaptedto buckle by having a portion of its column wall bulge outward away fromthe column interior.
 19. A yieldable cushioning element as recited inclaim 1, wherein at least one of said columns is adapted to buckle byhaving a portion of its column wall bulge inward toward the columninterior.
 20. A yieldable cushioning element as recited in claim 1,wherein at least one of said columns is adapted to yield along itslongitudinal axis by buckling of its column wall.
 21. A yieldablecushioning element as recited in claim 1, wherein the cushioning elementhas a total volume contained within the boundaries of the cushioningelement top, bottom and outer periphery and wherein said cushioningelement total volume is occupied by not more than about 50% by volume ofcushioning medium.
 22. A yieldable cushioning element as recited inclaim 1, wherein said cushioning medium has a Shore A hardness of lessthan about
 15. 23. A yieldable cushioning element as recited in claim 1,wherein said cushioning medium has a Shore A hardness of less than about3.
 24. A yieldable cushioning element as recited in claim 1, whereinsaid cushioning medium comprises a triblock copolymer and a plasticizer.25. A yieldable cushioning element as recited in claim 24, wherein saidcushioning medium comprises about one part by weight triblock copolymerand about one to about 25 parts by weight plasticizer, based on thetotal weight of the cushioning medium.
 26. A yieldable cushioningelement as recited in claim 25, wherein said copolymer is selected fromthe group consisting of polystyrene-poly(ethylene/butylene)-polystyrene,polystyrene-polyethylene-polystyrene, medium includes a blowing agentsuch as SAFOAM® FP-40, which is added to the non-liquidpolystyrene-polypropylene-polystyrene,polystyrene-polybutadiene-polystyrene,polystyrene-polybutylene-polystyrene,polystyrene-polyisoprene-polystyrene,polystyrene-poly(ethylene/propylene)-polystyrene,polystyrene-poly(isoprene+butadiene)-polystyrene andpolystyrene-poly(ethylene/butylene+ethylene/propylene)-polystyrene. 27.A yieldable cushioning element as recited in claim 25, wherein saidcopolymer is polystyrene-hydrogenatedpoly(isoprene+butadiene)-polystyrene.
 28. A yieldable cushioning elementas recited in claim 25, wherein said copolymer ispolystyrene-poly(ethylene/butylene)-polystyrene.
 29. A yieldablecushioning element as recited in claim 1, wherein said cushioning mediumcomprises a gelatinous visco-elastomer.
 30. A yieldable cushioningelement as recited in claim 29, and further comprising a cover.
 31. Ayieldable cushioning element as recited in claim 1, wherein saidcushioning medium is a lightweight flowable cushioning materialcontained within an elastomeric cover.
 32. A yieldable cushioncomprising:a cushioning element having a top, a bottom, a center and anouter periphery, said cushioning element comprising a quantity of gelcushioning media and a plurality of contiguous, adjacent hollow columnslocated within said cushioning media, said columns each having a columninterior, a column wall, and a longitudinal axis, wherein a plurality ofsaid columns are positioned such that said column axis is generallyparallel to a compressive force exerted on said top of said cushioningelement by a cushioned object in contact therewith; wherein at least oneother of said columns is positioned such that said longitudinal axis ofsaid other column is generally non-parallel to a compressive forceexerted on said top of said cushioning element by a cushioned object incontact therewith; wherein said cushion is responsive to the compressiveforce exerted thereon; and wherein said yieldability of the cushionresults from said cushioning media being compressible and from saidcolumns being bucklable, so that the cushion is able to substantiallyconform to the shape of the cushioned object.
 33. A yieldable cushioningelement that includes a flexible, resilient, gel cushioning media havingshape memory and being substantially solid and non-flowable attemperatures below 130 degrees Fahrenheit, the cushioning elementcomprising:a quantity of cushioning medium formed to have a top, abottom, and an outer periphery, said cushioning medium being deformableso that it will deform under the compressive force of a cushionedobject, a plurality of hollow columns formed in said cushioning medium,each of said columns having a longitudinal axis along its length, eachof said columns having a column wall which defines a column interior,and each of said columns having two ends; wherein the cushioning elementis adapted to have a cushioned object placed directly or indirectly incontact with said top; wherein each of said column ends is positioned attwo different points of said column axis; wherein a plurality of saidcolumns are positioned within said cushioning medium such that saidcolumn axes are positioned generally parallel to the direction of acompressive force exerted on the cushioning element by a cushionedobject in contact with said cushioning medium; wherein at least one ofsaid column walls is capable of buckling beneath a protuberance that islocated on the cushioned object; and wherein said cushioning mediumexhibits elastomeric properties.
 34. A yieldable cushioning element thatincludes a flexible, resilient, gel cushioning media having shape memoryand being substantially solid and non-flowable at temperatures below 130degrees Fahrenheit, the cushioning element comprising:a quantity ofcushioning medium formed to have a top, a bottom, and an outerperiphery, said cushioning medium being deformable so that it willdeform under the compressive force of a cushioned object, a plurality ofhollow columns formed in said cushioning medium, each of said columnshaving a longitudinal axis along its length, each of said columns havinga column wall which defines a column interior, and each of said columnshaving two ends; wherein the cushioning element is adapted to have acushioned object placed directly or indirectly in contact with said top;wherein each of said column ends is positioned at two different pointsof said column axis; wherein a plurality of said columns are positionedwithin said cushioning medium such that said column axes are positionedgenerally parallel to the direction of a compressive force exerted onthe cushioning element by a cushioned object in contact with saidcushioning medium; wherein at least one of said column walls is capableof buckling beneath a protuberance that is located on the cushionedobject; and wherein said cushioning medium exhibits visco-elastomericproperties.
 35. A yieldable cushioning element comprising:a quantity ofa first cushioning medium formed to have a top, a bottom, and an outerperiphery and a hollow center, a quantity of a second cushioning mediumdisposed within said first cushioning medium, said second cushioningmedium being deformable so that it will deform under the compressiveforce of a cushioned object, a plurality of hollow columns formed insaid first cushioning medium, each of said columns having a longitudinalaxis along its length, each of said columns having a column wall whichdefines a column interior, and each of said columns having two ends;wherein the cushioning element is adapted to have a cushioned objectplaced directly or indirectly in contact with said top; wherein each ofsaid column ends is positioned at two different points of said columnaxis; wherein a plurality of said columns are positioned within thecushion such that said column axes are positioned generally parallel tothe direction of a compressive force exerted on the cushioning elementby a cushioned object in contact with the cushion; wherein at least oneof said column walls is capable of buckling beneath a protuberance thatis located on the cushioned object; and wherein said second cushioningmedium is a gel cushioning medium.
 36. A yieldable cushioning elementcomprising:a quantity of gel cushioning medium formed to have a top, abottom, and an outer periphery, said cushioning medium being deformableso that it will deform under the compressive force of a cushionedobject, a coating material adhered to said top, said bottom and saidouter periphery, a plurality of hollow columns formed in said cushioningmedium, each of said columns having a longitudinal axis along itslength, each of said columns having a column wall which defines a columninterior, and each of said columns having two ends; wherein thecushioning element is adapted to have a cushioned object placed directlyor indirectly in contact with said top; wherein each of said column endsis positioned at two different points of said column axis; wherein aplurality of said columns are positioned within said cushioning mediumsuch that said column axes are positioned generally parallel to thedirection of a compressive force exerted on the cushioning element by acushioned object in contact with said cushioning medium; and wherein atleast one of said column walls is capable of buckling beneath aprotuberance that is located on the cushioned object.
 37. A yieldablecushioning element comprising:a quantity of gel cushioning medium formedto have a top, a bottom, and an outer periphery, said cushioning mediumbeing deformable so that it will deform under the compressive force of acushioned object, a first plurality of hollow columns formed in saidcushioning medium, each of said first columns having a firstlongitudinal axis along its length, each of said first columns having afirst column wall which defines a first column interior, and each ofsaid first columns having two ends; a second plurality of hollow columnsformed in said cushioning medium, each of said second columns having asecond longitudinal axis along its length, each of said second columnshaving a second column wall which defines a second interior, and each ofsaid second columns having two ends; wherein the cushioning element isadapted to have a cushioned object placed directly or indirectly incontact with said top; wherein each of said first column ends ispositioned at two different points of said column axis; wherein aplurality of said first columns are positioned within said cushioningmedium such that said first column axes are positioned generallyparallel to the direction of a compressive force exerted on thecushioning element by a cushioned object in contact with said cushioningmedium; wherein a plurality of said second columns are positioned withinsaid cushioning medium such that said second column axes are positionedgenerally parallel to one another and generally non-parallel to saidfirst column axes; and wherein at least one of said first column wallsis capable of buckling beneath a protuberance that is located on thecushioned object.
 38. A yieldable cushioning element as recited in claim37, wherein at least one of said first columns intersects at least oneof said second columns.